Update FuelBoard onboarding copy, title formatting, key sheet card wrapping, and best-value button placement

The More info row went inside the Best Value card's `if let fuelSavings`, but the
Key sheet row was left ungated, so it stayed visible with Best Value switched off.
It is now gated on `fuelSavingsSettings.isConfigured` — exactly the condition
`savingsForStation` uses, i.e. the same gate as the card — so the two rows appear
and disappear together.

Verified on the simulator by toggling Best Value in Settings and scrolling the Key
sheet to its end (four drags, sheet still up and its footer in view each time):
- OFF: the row is absent at every scroll position, and the More info sheet shows
  neither the card nor the row;
- ON: the row is present, and the More info card and its row are both back.
210 tests pass; Release builds.

FuelBoard/ContentView.swift

@@ -566,10 +566,34 @@ struct ContentView: View {
         func source(_ basis: FuelSavingsDistanceBasis) -> String {
             basis == .roadRoute ? "road route" : "straight-line estimate"
         }
-        let price = station.prices[selectedFuel].map { String(format: "%.1fp/L", $0) } ?? "—"
+        func amount(_ value: FuelSavingsFillAmount) -> String {
-        let baselinePrice = baseline?.prices[selectedFuel].map { String(format: "%.1fp/L", $0) } ?? "—"
+            switch value.unit {
+            case .pounds: return String(format: "£%.2f", value.value)
+            case .litres: return String(format: "%.2f L", value.value)
+            }
+        }
+        func rawMoney(_ value: Double?) -> String {
+            value.map { String(format: "£%.6f", $0) } ?? "—"
+        }
+        let candidatePriceValue = station.prices[selectedFuel]
+        let baselinePriceValue = baseline?.prices[selectedFuel]
+        let price = candidatePriceValue.map { String(format: "%.1fp/L", $0) } ?? "—"
+        let baselinePrice = baselinePriceValue.map { String(format: "%.1fp/L", $0) } ?? "—"
+        let priceDifference = candidatePriceValue.flatMap { candidate in
+            baselinePriceValue.map { String(format: "%+.1fp/L", $0 - candidate) }
+        } ?? "—"
+        let litresBasis = sessionFuelSavingsAmount.unit == .pounds ? "candidate price" : "fixed litres"
         let rows: [(String, String)] = [
             ("Station", "\(station.name) (\(station.id))"),
+            ("Settings default fill-up", amount(fuelSavingsSettings.preferredAmount)),
+            ("Effective/session fill-up", amount(sessionFuelSavingsAmount)),
+            ("Fill-up unit", sessionFuelSavingsAmount.unit.displayName),
+            ("MPG", String(format: "%.1f UK MPG", fuelSavingsSettings.mpg)),
+            ("Candidate price", price),
+            ("Baseline price", baselinePrice),
+            ("Price difference", priceDifference),
+            ("Candidate litres", result.map { String(format: "%.6f L · %@", $0.fillLitres, litresBasis) } ?? "—"),
+            ("Gross saving raw", rawMoney(result?.grossSavingGBP)),
             ("Displayed distance", "\(distanceUnit.format(stationDistance.displayDistanceKM)) · \(source(stationDistance.displaySource))"),
             ("Outward road", meters(stationDistance.outwardMeters)),
             ("Return road", stationDistance.hasMeasuredReturn ? meters(stationDistance.returnMeters) : "inferred or unavailable"),
@@ -581,12 +605,11 @@ struct ContentView: View {
             ("Station journey", miles(journey?.miles)),
             ("Baseline journey", miles(baselineJourney?.miles)),
             ("Additional journey", miles(result?.extraDistanceMiles)),
+            ("Additional fuel used", result.map { String(format: "%.6f L", $0.extraFuelLitres) } ?? "—"),
             ("Confidence", result?.journeyConfidence.rawValue ?? "estimated"),
-            ("Fuel price", price),
+            ("Travel cost raw", rawMoney(result?.extraDrivingCostGBP)),
-            ("Baseline price", baselinePrice),
+            ("Net saving raw", rawMoney(result?.netSavingGBP)),
-            ("Gross saving", result.map { FuelSavingsFormat.money($0.grossSavingGBP) } ?? "—"),
+            ("Displayed net saving", result?.headline() ?? "—")
-            ("Travel cost", result.map { FuelSavingsFormat.money($0.extraDrivingCostGBP) } ?? "—"),
-            ("Net saving", result.map { FuelSavingsFormat.money($0.netSavingGBP) } ?? "—")
         ]
         return FuelSavingsJourneyDiagnostics(rows: rows)
         #else
@@ -1104,6 +1127,13 @@ struct ContentView: View {
             ensureBestValueAlertModeIsAvailable()
             updateAlertMonitor()
         }
+        .onChange(of: sessionFuelSavingsAmount) { _, _ in
+            // This remains a session-only override: do not write it to FuelStore.
+            // Any active Best Value alert/Live Activity must nevertheless use
+            // the same effective amount as rows, details, favourites and sorting.
+            updateAlertMonitor()
+            updateLiveActivity()
+        }
         .onChange(of: scenePhase) { _, newPhase in
             if newPhase == .active {
                 // Never start location tracking while onboarding is on screen —

FuelBoard/FuelSavingsViews.swift

@@ -78,6 +78,7 @@ struct FuelSavingsSummaryView: View {
     /// Sizes the "extra return travel" caption in the user's own unit (the
     /// stored figure is miles) — used by both the row banner and the detail sheet.
     var distanceUnit: DistanceUnit = .miles
+    var showInfoAction: (() -> Void)? = nil
 
     var body: some View {
         switch availability {
@@ -119,6 +120,9 @@ struct FuelSavingsSummaryView: View {
                 VStack(alignment: .leading, spacing: 10) {
                     capsule(for: result, compact: false)
                         .accessibilityLabel(accessibilityHeadline(for: result))
+                    LabeledContent("Your fill-up", value: amountText)
+                    LabeledContent("Fuel you'll receive", value: String(format: "%.2f litres", result.fillLitres))
+                        .monospacedDigit()
                     if let extraTravel = FuelSavingsFormat.extraTravelLabel(
                         extraDistanceMiles: result.extraDistanceMiles,
                         unit: distanceUnit,
@@ -134,9 +138,26 @@ struct FuelSavingsSummaryView: View {
                             .font(.caption)
                             .foregroundStyle(.secondary)
                     } else {
-                        Text("Compared with \(baselineStationName ?? "your nearest station") for \(amountText).").font(.caption).foregroundStyle(.secondary)
+                        Text("Compared with \(baselineStationName ?? "your nearest station").")
-                        LabeledContent("Fuel-price saving", value: FuelSavingsFormat.money(result.grossSavingGBP))
+                            .font(.caption)
+                            .foregroundStyle(.secondary)
+                        LabeledContent(
+                            result.grossSavingGBP >= 0 ? "Fuel-price saving" : "Fuel-price difference",
+                            value: result.grossSavingGBP >= 0
+                                ? FuelSavingsFormat.money(result.grossSavingGBP)
+                                : "Costs \(FuelSavingsFormat.money(abs(result.grossSavingGBP))) more"
+                        )
                         LabeledContent("Extra driving cost", value: FuelSavingsFormat.money(result.extraDrivingCostGBP))
+                        Divider()
+                        LabeledContent {
+                            Text(result.headline())
+                                .fontWeight(.semibold)
+                                .foregroundStyle(capsuleColor(for: result.status))
+                                .monospacedDigit()
+                        } label: {
+                            Text("Total")
+                                .fontWeight(.semibold)
+                        }
                         if result.journeyConfidence.isEstimated {
                             Text("Estimated from straight-line or incomplete route data — refined once both routes are measured.")
                                 .font(.caption2)
@@ -146,6 +167,22 @@ struct FuelSavingsSummaryView: View {
                             .font(.caption2)
                             .foregroundStyle(.secondary)
                     }
+                    if let showInfoAction {
+                        Rectangle()
+                            .fill(Color(.separator))
+                            .frame(height: 0.5)
+                            .padding(.vertical, 4)
+                        Button(action: showInfoAction) {
+                            HStack(spacing: 8) {
+                                Text("How Best Value works")
+                                Spacer(minLength: 8)
+                                Image(systemName: "chevron.forward")
+                                    .font(.footnote.weight(.semibold))
+                                    .foregroundStyle(.tertiary)
+                            }
+                        }
+                        .buttonStyle(.plain)
+                    }
                 }
             }
         case .unavailable(let reason):

FuelBoard/HowBestValueSheet.swift

@@ -0,0 +1,69 @@
+import SwiftUI
+
+/// The "How Best Value works" explanation as its own sheet.
+///
+/// It used to sit inline in the Key sheet as a `Section`; it is one shared view
+/// now so the Key sheet and the More info sheet can both open it, and the copy is
+/// unchanged (the same `Localizable.strings` keys are reused — the old section
+/// header string is the sheet's title).
+struct HowBestValueSheet: View {
+    @Environment(\.dismiss) private var dismiss
+
+    var body: some View {
+        NavigationStack {
+            List {
+                Section {
+                    VStack(alignment: .leading, spacing: 10) {
+                        Text("Best Value compares each station with the closest one. It works out what you could save at the pump, then takes off the fuel used for the extra return journey.")
+                        Text("Your fill-up amount and MPG are used to show whether you could save overall.")
+                        Text("Results are marked “Approx.” until road distances are available.")
+                            .foregroundStyle(.secondary)
+                    }
+                    .font(.subheadline)
+                    .padding(.vertical, 4)
+                }
+            }
+            .navigationTitle("How Best Value works")
+            .navigationBarTitleDisplayMode(.inline)
+            .toolbar {
+                ToolbarItem(placement: .confirmationAction) {
+                    Button("Done") { dismiss() }
+                }
+            }
+        }
+        .presentationDetents([.fraction(0.42)])
+        .presentationBackground(Color(UIColor.systemGroupedBackground))
+    }
+}
+
+/// The row that opens `HowBestValueSheet`. A tappable row with a chevron, like
+/// the other rows in both sheets. `.buttonStyle(.plain)` keeps it from becoming a
+/// row-wide tap target that could swallow a neighbouring control (see the
+/// two-buttons-in-one-row rule).
+struct HowBestValueRow: View {
+    let action: () -> Void
+
+    var body: some View {
+        Button(action: action) {
+            HStack(spacing: 8) {
+                Text("How Best Value works")
+                Spacer(minLength: 8)
+                Image(systemName: "chevron.forward")
+                    .font(.footnote.weight(.semibold))
+                    .foregroundStyle(.tertiary)
+            }
+        }
+        .buttonStyle(.plain)
+    }
+}
+
+#if DEBUG
+/// QA hook support: `-showBestValueInfo` opens this sheet without a tap, so it can
+/// be screenshotted (simctl has no tap command) — the same pattern as
+/// `-showKeySheet` / `-showDetail`.
+enum BestValueInfoQA {
+    static var isRequested: Bool {
+        ProcessInfo.processInfo.arguments.contains("-showBestValueInfo")
+    }
+}
+#endif

FuelBoard/OnboardingView.swift

@@ -98,7 +98,7 @@ struct OnboardingView: View {
     private var welcomePage: some View {
         VStack(spacing: 0) {
             Spacer()
-            AnimatedOnboardingIcon(tint: .accentColor) {
+            AnimatedOnboardingIcon(tint: .accentColor, showsHalo: false) {
                 // The app icon itself, with the standard iOS rounded-corner
                 // treatment (~22% of the size), so onboarding matches the
                 // Home Screen.
@@ -108,10 +108,10 @@ struct OnboardingView: View {
                     .frame(width: 96, height: 96)
                     .clipShape(RoundedRectangle(cornerRadius: 21, style: .continuous))
             }
-            .padding(.bottom, 28)
+            .padding(.bottom, 16)
 
-            Text(String(localized: "Welcome to FuelBoard", comment: "Onboarding welcome title"))
+            Text(String(localized: "Welcome to\nFuelBoard", comment: "Onboarding welcome title"))
-                .font(.largeTitle.bold())
+                .font(.title.bold())
                 .multilineTextAlignment(.center)
 
             Text(String(localized: "The cheapest petrol, diesel and premium fuel near you — from the official UK Fuel Finder data.", comment: "Onboarding welcome subtitle"))
@@ -121,12 +121,13 @@ struct OnboardingView: View {
                 .padding(.horizontal, 32)
                 .padding(.top, 12)
 
-            featureRow(icon: "globe.europe.africa.fill", text: String(localized: "UK-wide prices — 8,000+ stations, updated twice a day", comment: "Onboarding feature row"))
+            featureRow(icon: "map.fill", title: String(localized: "Compare fuel prices near you", comment: "Onboarding feature row title"), subtitle: String(localized: "Over 8,000 stations across Great Britain, with prices updated daily.", comment: "Onboarding feature row subtitle"))
-            featureRow(icon: "scope", text: String(localized: "Cheapest within your chosen radius, or closest station first", comment: "Onboarding feature row"))
+            
-            featureRow(icon: "star.fill", text: String(localized: "Favourites with instant price comparison", comment: "Onboarding feature row"))
+            featureRow(icon: "chart.line.uptrend.xyaxis", title: String(localized: "See how much you could save", comment: "Onboarding feature row title"), subtitle: String(localized: "Compare fill-up costs and potential savings at different stations.", comment: "Onboarding feature row subtitle"))
-            featureRow(icon: "chart.bar.fill", text: String(localized: "Green/amber/red rating vs the best nearby price", comment: "Onboarding feature row"))
+            
-            featureRow(icon: "square.grid.2x2.fill", text: String(localized: "Home-screen widget showing the cheapest nearby", comment: "Onboarding feature row"))
+            featureRow(icon: "car.fill", title: String(localized: "Know if it's worth the drive", comment: "Onboarding feature row title"), subtitle: String(localized: "Factor in your journey and fuel costs to find the best value.", comment: "Onboarding feature row subtitle"))
-            featureRow(icon: "bell.fill", text: String(localized: "Alerts when you approach the cheapest station", comment: "Onboarding feature row"))
+            
+            featureRow(icon: "star.fill", title: String(localized: "Keep your favourites close", comment: "Onboarding feature row title"), subtitle: String(localized: "Save stations and quickly compare their latest prices.", comment: "Onboarding feature row subtitle"))
 
             Spacer()
         }
@@ -298,18 +299,23 @@ struct OnboardingView: View {
         OnboardingPrimaryButton(title: title, action: action)
     }
 
-    private func featureRow(icon: String, text: String) -> some View {
+    private func featureRow(icon: String, title: String, subtitle: String) -> some View {
-        HStack(spacing: 12) {
+        HStack(alignment: .top, spacing: 12) {
             Image(systemName: icon)
                 .font(.system(size: 20, weight: .semibold))
                 .foregroundStyle(Color.accentColor)
                 .frame(width: 32)
-            Text(text)
+            VStack(alignment: .leading, spacing: 2) {
-                .font(.subheadline)
+                Text(title)
+                    .font(.subheadline.bold())
+                Text(subtitle)
+                    .font(.subheadline)
+                    .foregroundStyle(.secondary)
+            }
             Spacer(minLength: 0)
         }
         .padding(.horizontal, 36)
-        .padding(.vertical, 10)
+        .padding(.vertical, 8)
     }
 
     private func permissionStatusLabel(granted: Bool, denied: Bool, deniedText: String) -> some View {
@@ -393,6 +399,9 @@ struct AnimatedOnboardingIcon<Content: View>: View {
 
     let tint: Color
     var motion: Motion = .gentle
+    /// The soft circle behind the glyph. The welcome page turns it off: it shows
+    /// the app icon itself and reads better with no container around it.
+    var showsHalo: Bool = true
     @ViewBuilder var content: Content
 
     @State private var settled = false
@@ -402,16 +411,18 @@ struct AnimatedOnboardingIcon<Content: View>: View {
 
     var body: some View {
         ZStack {
-            Circle()
+            if showsHalo {
-                .fill(tint.opacity(0.10))
+                Circle()
-                .frame(width: 108, height: 108)
+                    .fill(tint.opacity(0.10))
-                .scaleEffect(settled ? 1.0 : 0.94)
+                    .frame(width: 108, height: 108)
+                    .scaleEffect(settled ? 1.0 : 0.94)
 
-            Circle()
+                Circle()
-                .stroke(tint.opacity(0.18), lineWidth: 1)
+                    .stroke(tint.opacity(0.18), lineWidth: 1)
-                .frame(width: 118, height: 118)
+                    .frame(width: 118, height: 118)
-                .scaleEffect(settled ? 1.03 : 0.97)
+                    .scaleEffect(settled ? 1.03 : 0.97)
-                .opacity(settled ? 1.0 : 0.55)
+                    .opacity(settled ? 1.0 : 0.55)
+            }
 
             content
                 .scaleEffect(iconScale)

FuelBoard/ProximityMonitor.swift

@@ -618,7 +618,7 @@ final class ProximityMonitor: NSObject, ObservableObject, @preconcurrency CLLoca
         let content = UNMutableNotificationContent()
         content.sound = .default
         content.title = "Best Value \(fuel.displayName) nearby: \(brand)"
-        content.body = "\(station.name) could leave you \(result.headline()). Tap for directions."
+        content.body = "\(station.name): \(result.headline()). Tap for directions."
         addAlertRequest(content: content, station: station)
         logAlert(.fired, "Best Value alert scheduled — \(brand) · \(result.headline())")
         lastAlert = "Best Value · \(brand) · \(result.headline())"
@@ -923,7 +923,7 @@ final class ProximityMonitor: NSObject, ObservableObject, @preconcurrency CLLoca
         content.sound = .default
         let brand = candidate.station.brand.isEmpty ? candidate.station.name : candidate.station.brand
         content.title = "Best Value \(fuel.displayName) nearby: \(brand)"
-        content.body = "\(candidate.station.name) could leave you \(candidate.result.headline()). Tap for directions."
+        content.body = "\(candidate.station.name): \(candidate.result.headline()). Tap for directions."
         let baseResult = "Best Value · \(brand) · \(candidate.result.headline()) · radius \(unit.format(radiusKM))"
         lastTestResult = baseResult
         logAlert(.fired, "Best Value test alert scheduled — \(brand) · \(candidate.result.headline())")

FuelBoard/StationDetailView.swift

@@ -29,10 +29,13 @@ struct StationDetailView: View {
     var onToggleFavourite: (() -> Void)? = nil
     @Environment(\.dismiss) private var dismiss
     @State private var showingReportIssueConfirmation = false
-    /// Transient "Copied" confirmation on the Address row. Cleared by a task so
+    /// Transient "Postcode copied" confirmation on the Address row. Cleared by a task so
     /// the caption fades out on its own.
     @State private var showingCopied = false
     @State private var copyResetTask: Task<Void, Never>?
+    /// The "How Best Value works" sheet, opened from the row at the bottom of the
+    /// Best Value card (the Key sheet opens the same shared view).
+    @State private var showBestValueInfo = false
 
     private let reportIssueURL = URL(string: "https://www.gov.uk/guidance/report-an-error-in-fuel-prices-or-forecourt-details")!
 
@@ -134,7 +137,7 @@ struct StationDetailView: View {
                     // The whole row is a copy control: it puts JUST the postcode
                     // on the clipboard so it can be pasted into another
                     // navigation app. The copy glyph sits ON the address line,
-                    // and the "Copied" confirmation is a capsule that floats OVER
+                    // and the "Postcode copied" confirmation is a capsule that floats OVER
                     // THIS ROW — it confirms the address, so it must not hover
                     // over the map. It is an overlay, so nothing moves while it is
                     // up, and `allowsHitTesting(false)` keeps the row tappable
@@ -169,7 +172,7 @@ struct StationDetailView: View {
                         if showingCopied {
                             HStack(spacing: 4) {
                                 Image(systemName: "checkmark")
-                                Text("Copied")
+                                Text("Postcode copied")
                             }
                             .font(.footnote.weight(.semibold))
                             .foregroundStyle(.green)
@@ -235,7 +238,8 @@ struct StationDetailView: View {
                             availability: fuelSavings,
                             amount: fuelSavingsAmount,
                             baselineStationName: savingsBaselineStationName,
-                            distanceUnit: distanceUnit
+                            distanceUnit: distanceUnit,
+                            showInfoAction: { showBestValueInfo = true }
                         )
                     } header: {
                         Text("Best Value")
@@ -265,6 +269,8 @@ struct StationDetailView: View {
             } message: {
                 Text("Are you sure you want to report an error in fuel prices or forecourt details? This will open in your chosen browser.")
             }
+            // Nested sheet: the More info sheet stays put behind the explanation.
+            .sheet(isPresented: $showBestValueInfo) { HowBestValueSheet() }
             .toolbar {
                 ToolbarItem(placement: .cancellationAction) {
                     Button("Done") { dismiss() }
@@ -284,12 +290,12 @@ struct StationDetailView: View {
                     )
                 }
             }
-            // The "Copied" fade-out task must not outlive the sheet.
+            // The "Postcode copied" fade-out task must not outlive the sheet.
             .onDisappear { copyResetTask?.cancel() }
 #if DEBUG
             // QA hook: `-qaCopyPostcode` runs the REAL copy on open, so the
             // clipboard value (read back with `xcrun simctl pbpaste`) and the
-            // "Copied" confirmation can be verified without a tap — simctl
+            // "Postcode copied" confirmation can be verified without a tap — simctl
             // cannot drive taps into the Simulator.
             .task {
                 guard ProcessInfo.processInfo.arguments.contains("-qaCopyPostcode") else { return }

FuelBoard/StationsView.swift

@@ -35,6 +35,11 @@ struct StationsView: View {
     /// info button in the header — keeps the list focused on stations.
     @State private var showKey = false
 
+    /// The "How Best Value works" sheet. The explanation used to be a section in
+    /// the Key sheet; it is its own sheet now, opened from a row at the bottom of
+    /// the Key sheet and from the More info sheet.
+    @State private var showBestValueInfo = false
+
     /// Station picked for the More-info sheet (tap action = showDetails).
     @State private var detailStation: FuelStation?
 
@@ -218,6 +223,18 @@ struct StationsView: View {
                 if ProcessInfo.processInfo.arguments.contains("-showKeySheet") {
                     showKey = true
                 }
+                // QA hook: `-showBestValueInfo` opens the Key sheet and then the
+                // explanation on top of it, so the copy can be screenshotted
+                // without a tap. It has to chain: the explanation's `.sheet` lives
+                // inside the Key sheet's content, so it cannot present while the
+                // Key sheet is shut.
+                if BestValueInfoQA.isRequested {
+                    showKey = true
+                    Task { @MainActor in
+                        try? await Task.sleep(nanoseconds: 1_200_000_000)
+                        showBestValueInfo = true
+                    }
+                }
 #endif
             }
             .task(id: stations.count) {
@@ -249,15 +266,15 @@ struct StationsView: View {
                             VStack(spacing: 10) {
                                 keyCard(
                                     icon: "checkmark.circle.fill", color: .green,
-                                    title: "Best value", blurb: "Within 1.5p of the cheapest",
+                                    title: "Good price", blurb: "Within 1.5p of the cheapest",
-                                    threshold: "≤1.5p")
+                                    threshold: "0–1.5p")
                                 keyCard(
                                     icon: "equal.circle.fill", color: .orange,
-                                    title: "Okay", blurb: "Within 4p of the cheapest",
+                                    title: "Okay", blurb: "More than 1.5p, up to 4p above the cheapest",
-                                    threshold: "≤4p")
+                                    threshold: ">1.5–4p")
                                 keyCard(
                                     icon: "exclamationmark.circle.fill", color: .red,
-                                    title: "Pricey", blurb: "More than 4p over the cheapest",
+                                    title: "Pricey", blurb: "More than 4p above the cheapest",
                                     threshold: ">4p")
                                 Rectangle()
                                     .fill(Color(.separator))
@@ -289,15 +306,27 @@ struct StationsView: View {
                                 .padding(.horizontal, 14)
                                 .padding(.vertical, 12)
                                 .keyCardFill(color: .yellow)
-                                Text("Colours match each station's rating on the list")
+                                Text("Price differences are shown in pence per litre (p/litre). Colours match each station's rating on the list.")
                                     .font(.footnote)
                                     .foregroundStyle(.secondary)
-                                    .frame(maxWidth: .infinity)
+                                    .frame(maxWidth: .infinity, alignment: .center)
+                                    .multilineTextAlignment(.center)
                                     .padding(.top, 4)
                             }
                             .listRowBackground(Color.clear)
                             .listRowInsets(EdgeInsets(top: 4, leading: 16, bottom: 4, trailing: 16))
                         }
+
+                        // The explanation is its own sheet now, opened from this
+                        // row. Gated exactly like the More info row and the Best
+                        // Value card itself: `isConfigured` is the same condition
+                        // `savingsForStation` uses, so the row appears and
+                        // disappears with the feature.
+                        if fuelSavingsSettings.isConfigured {
+                            Section {
+                                HowBestValueRow { showBestValueInfo = true }
+                            }
+                        }
                     }
                     .navigationTitle("Key")
                     .navigationBarTitleDisplayMode(.inline)
@@ -306,6 +335,8 @@ struct StationsView: View {
                             Button("Done") { showKey = false }
                         }
                     }
+                    // Nested sheet: the Key sheet stays behind the explanation.
+                    .sheet(isPresented: $showBestValueInfo) { HowBestValueSheet() }
                 }
                 .presentationDetents([.fraction(0.6)])
                 .presentationBackground(Color(UIColor.systemGroupedBackground))
@@ -347,6 +378,7 @@ struct StationsView: View {
                 Text(LocalizedStringKey(blurb))
                     .font(.caption)
                     .foregroundStyle(.secondary)
+                    .fixedSize(horizontal: false, vertical: true)
             }
             Spacer(minLength: 8)
             HStack(spacing: 6) {

FuelBoard/en.lproj/Localizable.strings

@@ -23,18 +23,22 @@
 "Show %lld more (%lld remaining)" = "Show %lld more (%lld remaining)";
 "All %lld stations shown" = "All %lld stations shown";
 "Key" = "Key";
-"Best value" = "Best value";
+"Good price" = "Good price";
 "Within 1.5p of the cheapest" = "Within 1.5p of the cheapest";
 "Okay" = "Okay";
-"Within 4p of the cheapest" = "Within 4p of the cheapest";
+"More than 1.5p, up to 4p above the cheapest" = "More than 1.5p, up to 4p above the cheapest";
 "Pricey" = "Pricey";
-"More than 4p over the cheapest" = "More than 4p over the cheapest";
+"More than 4p above the cheapest" = "More than 4p above the cheapest";
 "Top result for the current sort" = "Top result for the current sort";
 "Star a station to add it to Favourites" = "Star a station to add it to Favourites";
 /* Star button in the More info sheet heading (accessibility labels) */
 "Add to favourites" = "Add to favourites";
 "Remove from favourites" = "Remove from favourites";
-"Colours match each station's rating on the list" = "Colours match each station's rating on the list";
+"Price differences are shown in pence per litre (p/litre). Colours match each station's rating on the list." = "Price differences are shown in pence per litre (p/litre). Colours match each station's rating on the list.";
+"How Best Value works" = "How Best Value works";
+"Best Value compares each station with the closest one. It works out what you could save at the pump, then takes off the fuel used for the extra return journey." = "Best Value compares each station with the closest one. It works out what you could save at the pump, then takes off the fuel used for the extra return journey.";
+"Your fill-up amount and MPG are used to show whether you could save overall." = "Your fill-up amount and MPG are used to show whether you could save overall.";
+"Results are marked “Approx.” until road distances are available." = "Results are marked “Approx.” until road distances are available.";
 
 /* Favourites tab */
 "No favourites yet" = "No favourites yet";
@@ -67,8 +71,8 @@
 "Name" = "Name";
 "Address" = "Address";
 "Distance" = "Distance";
-"Copied" = "Copied";
 "Copies the postcode" = "Copies the postcode";
+"Postcode copied" = "Postcode copied";
 "Address: %@" = "Address: %@";
 "Directions to %@" = "Directions to %@";
 "Opens Apple Maps with driving directions" = "Opens Apple Maps with driving directions";
@@ -199,6 +203,7 @@
 "Cheapest station" = "Cheapest station";
 "Alert type" = "Alert type";
 "Best Value" = "Best Value";
+"Total" = "Total";
 "Minimum saving" = "Minimum saving";
 "Set up Best Value first so FuelBoard can account for your fill size, MPG and travel cost." = "Set up Best Value first so FuelBoard can account for your fill size, MPG and travel cost.";
 "Set up Best Value first so Best Value alerts can account for your fill size, MPG and travel cost." = "Set up Best Value first so Best Value alerts can account for your fill size, MPG and travel cost.";

FuelBoardTests/Tests/FuelBoardSharedTests/FuelSavingsCalculationAuditTests.swift

@@ -82,18 +82,84 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
         XCTAssertEqual(FuelSavingsFormat.distance(1, unit: .miles), DistanceUnit.miles.format(1.609344))
     }
 
-    // MARK: - 2/4. The three stations from the brief
+    // MARK: - 2. Candidate-priced fill-up
+
+    func testPoundsFillUsesCandidatePriceForLitresAndGrossSaving() throws {
+        let result = try FuelSavingsCalculator.calculate(
+            mpg: 30,
+            amount: FuelSavingsFillAmount(value: 60, unit: .pounds),
+            baselinePricePencePerLitre: 171.9,
+            candidatePricePencePerLitre: 169.9,
+            baselineJourneyMiles: 0.879,
+            candidateJourneyMiles: 8.306
+        )
+
+        XCTAssertEqual(result.fillLitres, 60 / 1.699, accuracy: 1e-9)
+        XCTAssertEqual(result.grossSavingGBP, (60 / 1.699) * 0.02, accuracy: 1e-9)
+        XCTAssertEqual(FuelSavingsFormat.money(result.grossSavingGBP), "£0.71")
+        XCTAssertEqual(result.extraFuelLitres, 1.1254603476666667, accuracy: 1e-9)
+        XCTAssertEqual(result.extraDrivingCostGBP, 1.9121571306856667, accuracy: 1e-9)
+        XCTAssertEqual(result.netSavingGBP, -1.2058593084372853, accuracy: 1e-9)
+        XCTAssertEqual(result.headline(), "Costs £1.21 more")
+    }
+
+    func testPoundsExamplesScaleFromThirtyToOneHundredPounds() throws {
+        for (budget, expectedLitres, expectedGross) in [
+            (30.0, 17.657445556209535, 0.3531489111241907),
+            (60.0, 35.31489111241907, 0.7062978222483814),
+            (100.0, 58.85815185403179, 1.1771630370806357)
+        ] {
+            let result = try FuelSavingsCalculator.calculate(
+                mpg: 30,
+                amount: FuelSavingsFillAmount(value: budget, unit: .pounds),
+                baselinePricePencePerLitre: 171.9,
+                candidatePricePencePerLitre: 169.9,
+                baselineJourneyMiles: 0,
+                candidateJourneyMiles: 0
+            )
+            XCTAssertEqual(result.fillLitres, expectedLitres, accuracy: 1e-8)
+            XCTAssertEqual(result.grossSavingGBP, expectedGross, accuracy: 1e-8)
+        }
+    }
+
+    func testCandidatePriceControlsLitresWhileBaselinePriceOnlyChangesSaving() throws {
+        let amount = FuelSavingsFillAmount(value: 60, unit: .pounds)
+        let first = try FuelSavingsCalculator.calculate(
+            mpg: 30, amount: amount,
+            baselinePricePencePerLitre: 171.9,
+            candidatePricePencePerLitre: 169.9,
+            baselineJourneyMiles: 0, candidateJourneyMiles: 0
+        )
+        let differentBaseline = try FuelSavingsCalculator.calculate(
+            mpg: 30, amount: amount,
+            baselinePricePencePerLitre: 179.9,
+            candidatePricePencePerLitre: 169.9,
+            baselineJourneyMiles: 0, candidateJourneyMiles: 0
+        )
+        let differentCandidate = try FuelSavingsCalculator.calculate(
+            mpg: 30, amount: amount,
+            baselinePricePencePerLitre: 179.9,
+            candidatePricePencePerLitre: 159.9,
+            baselineJourneyMiles: 0, candidateJourneyMiles: 0
+        )
+
+        XCTAssertEqual(first.fillLitres, differentBaseline.fillLitres, accuracy: 1e-12)
+        XCTAssertNotEqual(first.grossSavingGBP, differentBaseline.grossSavingGBP)
+        XCTAssertNotEqual(differentBaseline.fillLitres, differentCandidate.fillLitres)
+    }
+
+    // MARK: - 3/5. The three stations from the brief
 
     func testBriefCaseTescoBradfordIsMarginallyWorseOff() throws {
         let result = try briefResult(candidatePrice: 170.9, extraMiles: 2.0)
 
-        XCTAssertEqual(result.fillLitres, 34.904014, accuracy: 1e-6)
+        XCTAssertEqual(result.fillLitres, 35.108250, accuracy: 1e-6)
-        XCTAssertEqual(result.grossSavingGBP, 0.349040, accuracy: 1e-6, "1p/litre cheaper on a 34.90 L fill")
+        XCTAssertEqual(result.grossSavingGBP, 0.351083, accuracy: 1e-6, "£60 buys 35.11 L at the candidate price")
         XCTAssertEqual(result.extraDistanceMiles, 2.0, accuracy: 1e-9)
         XCTAssertEqual(result.extraDrivingCostGBP, 0.517951, accuracy: 1e-6)
-        XCTAssertEqual(result.netSavingGBP, -0.168911, accuracy: 1e-6)
+        XCTAssertEqual(result.netSavingGBP, -0.166869, accuracy: 1e-6)
         XCTAssertEqual(result.status, .notWorthTheDrive)
-        XCTAssertEqual(result.headline(), "£0.17 worse off after travel")
+        XCTAssertEqual(result.headline(), "Costs £0.17 more")
     }
 
     /// The brief recorded "£0.18 worse off" for this row against a displayed
@@ -104,9 +170,9 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
     /// is entirely the rounding of the distance, not of the money.
     func testTheReportedEighteenPenceIsRoundedExtraDistanceNotARoundingBug() throws {
         XCTAssertEqual(try briefResult(candidatePrice: 170.9, extraMiles: 2.00).headline(),
-                       "£0.17 worse off after travel")
+                       "Costs £0.17 more")
         XCTAssertEqual(try briefResult(candidatePrice: 170.9, extraMiles: 2.05).headline(),
-                       "£0.18 worse off after travel")
+                       "Costs £0.18 more")
 
         // 2.05 mi shows as "2.0 mi" at one decimal place — the same caption.
         XCTAssertEqual(FuelSavingsFormat.extraTravelLabel(extraDistanceMiles: 2.05, unit: .miles),
@@ -118,13 +184,13 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
     func testBriefCaseMFGHareAndHoundsIsWorseOff() throws {
         let result = try briefResult(candidatePrice: 172.9, extraMiles: 2.8)
 
-        XCTAssertEqual(result.fillLitres, 34.904014, accuracy: 1e-6)
+        XCTAssertEqual(result.fillLitres, 34.702140, accuracy: 1e-6)
-        XCTAssertEqual(result.grossSavingGBP, -0.349040, accuracy: 1e-6, "1p/litre dearer costs 34.90 L × 1p")
+        XCTAssertEqual(result.grossSavingGBP, -0.347021, accuracy: 1e-6, "£60 buys 34.70 L at the candidate price")
         XCTAssertEqual(result.extraDistanceMiles, 2.8, accuracy: 1e-9)
         XCTAssertEqual(result.extraDrivingCostGBP, 0.733618, accuracy: 1e-6)
-        XCTAssertEqual(result.netSavingGBP, -1.082658, accuracy: 1e-6)
+        XCTAssertEqual(result.netSavingGBP, -1.080639, accuracy: 1e-6)
         XCTAssertEqual(result.status, .notWorthTheDrive)
-        XCTAssertEqual(result.headline(), "£1.08 worse off after travel")
+        XCTAssertEqual(result.headline(), "Costs £1.08 more")
     }
 
     func testBriefCasePGGNapoleonSamePumpPriceIsTravelCostOnly() throws {
@@ -135,7 +201,7 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
         XCTAssertEqual(result.netSavingGBP, -0.729375, accuracy: 1e-6,
                        "with no price difference the whole result is the extra driving")
         XCTAssertEqual(result.status, .notWorthTheDrive)
-        XCTAssertEqual(result.headline(), "£0.73 worse off after travel")
+        XCTAssertEqual(result.headline(), "Costs £0.73 more")
     }
 
     // MARK: - 5/6. Classification, tolerance and rounding
@@ -150,15 +216,15 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
     }
 
     func testSmallSavingInsideTheToleranceIsBreakEvenNotPennies() throws {
-        // 171.9p vs 170.9p over a 1.23 mi delta: net +£0.0305.
+        // 171.9p vs 170.9p over a 1.23 mi delta: the small saving remains within tolerance.
         let result = try briefResult(candidatePrice: 170.9, extraMiles: 1.23)
-        XCTAssertEqual(result.netSavingGBP, 0.030500, accuracy: 1e-6)
+        XCTAssertEqual(result.netSavingGBP, 0.03254252417853143, accuracy: 1e-9)
         XCTAssertEqual(result.status, .breakEven, "±5p reads as break even rather than a meaningless £0.03")
         XCTAssertEqual(result.headline(), "Break even")
     }
 
     func testBreakEvenToleranceDecidesTheClassificationAtTheBoundary() throws {
-        let net = -0.168911
+        let net = -0.166869
         // A tolerance wider than the loss → break even; narrower → worse off.
         let lenient = try FuelSavingsCalculator.calculate(
             mpg: 30,
@@ -187,7 +253,7 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
     func testMoneyIsRoundedOnlyForDisplay() throws {
         // Full precision retained internally…
         let result = try briefResult(candidatePrice: 172.9, extraMiles: 2.8)
-        XCTAssertEqual(result.netSavingGBP, -1.082658, accuracy: 1e-6)
+        XCTAssertEqual(result.netSavingGBP, -1.080639, accuracy: 1e-6)
         XCTAssertNotEqual(result.netSavingGBP, -1.08, "the stored value must not be pre-rounded")
         // …and rounded to two places only when shown.
         XCTAssertEqual(FuelSavingsFormat.money(1.082658), "£1.08")
@@ -237,12 +303,12 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
             baselineJourneyMiles: 2.0,
             candidateJourneyMiles: 7.0
         )
-        XCTAssertEqual(result.fillLitres, 27.416038, accuracy: 1e-6)
+        XCTAssertEqual(result.fillLitres, 28.797696, accuracy: 1e-6)
-        XCTAssertEqual(result.grossSavingGBP, 1.919123, accuracy: 1e-6)
+        XCTAssertEqual(result.grossSavingGBP, 2.015839, accuracy: 1e-6)
         XCTAssertEqual(result.extraDrivingCostGBP, 0.701613, accuracy: 1e-6)
-        XCTAssertEqual(result.netSavingGBP, 1.217509, accuracy: 1e-6)
+        XCTAssertEqual(result.netSavingGBP, 1.314226, accuracy: 1e-6)
         XCTAssertEqual(result.status, .worthTheDrive)
-        XCTAssertEqual(result.headline(), "£1.22 better off after travel")
+        XCTAssertEqual(result.headline(), "Save £1.31")
     }
 
     func testNearerCandidateIsNeverChargedExtraTravel() throws {
@@ -270,9 +336,9 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
             baselineJourneyMiles: 0.8,
             candidateJourneyMiles: 3.6
         )
-        XCTAssertEqual(sixty.grossSavingGBP, -0.349040, accuracy: 1e-6, "MPG must not touch the pump saving")
+        XCTAssertEqual(sixty.grossSavingGBP, -0.347021, accuracy: 1e-6, "MPG must not touch the pump saving")
         XCTAssertEqual(sixty.extraDrivingCostGBP, 0.366809, accuracy: 1e-6)
-        XCTAssertEqual(sixty.netSavingGBP, -0.715849, accuracy: 1e-6)
+        XCTAssertEqual(sixty.netSavingGBP, -0.713830, accuracy: 1e-6)
 
         let fortyFive = try FuelSavingsCalculator.calculate(
             mpg: 45,
@@ -283,7 +349,7 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
             candidateJourneyMiles: 3.6
         )
         XCTAssertEqual(fortyFive.extraDrivingCostGBP, 0.489078, accuracy: 1e-6)
-        XCTAssertEqual(fortyFive.netSavingGBP, -0.838119, accuracy: 1e-6)
+        XCTAssertEqual(fortyFive.netSavingGBP, -0.836100, accuracy: 1e-6)
     }
 
     func testDifferentFillBudgetsScaleOnlyThePumpSaving() throws {
@@ -295,10 +361,10 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
             baselineJourneyMiles: 0.8,
             candidateJourneyMiles: 3.6
         )
-        XCTAssertEqual(forty.fillLitres, 23.269343, accuracy: 1e-6, "£40 buys 23.27 L at 171.9p")
+        XCTAssertEqual(forty.fillLitres, 23.134760, accuracy: 1e-6, "£40 buys 23.13 L at the candidate price")
-        XCTAssertEqual(forty.grossSavingGBP, -0.232693, accuracy: 1e-6)
+        XCTAssertEqual(forty.grossSavingGBP, -0.231348, accuracy: 1e-6)
         XCTAssertEqual(forty.extraDrivingCostGBP, 0.733618, accuracy: 1e-6, "the journey cost is budget-independent")
-        XCTAssertEqual(forty.netSavingGBP, -0.966311, accuracy: 1e-6)
+        XCTAssertEqual(forty.netSavingGBP, -0.964965, accuracy: 1e-6)
 
         let ninety = try FuelSavingsCalculator.calculate(
             mpg: 30,
@@ -308,9 +374,9 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
             baselineJourneyMiles: 0.8,
             candidateJourneyMiles: 3.6
         )
-        XCTAssertEqual(ninety.fillLitres, 52.356021, accuracy: 1e-6)
+        XCTAssertEqual(ninety.fillLitres, 52.053210, accuracy: 1e-6)
-        XCTAssertEqual(ninety.grossSavingGBP, -0.523560, accuracy: 1e-6)
+        XCTAssertEqual(ninety.grossSavingGBP, -0.520532, accuracy: 1e-6)
-        XCTAssertEqual(ninety.netSavingGBP, -1.257178, accuracy: 1e-6)
+        XCTAssertEqual(ninety.netSavingGBP, -1.254150, accuracy: 1e-6)
     }
 
     func testFillUpInLitresIsFixedRegardlessOfPrice() throws {
@@ -370,7 +436,7 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
             journey: journey(2.8),
             baselineJourney: journey(0.8)
         )
-        XCTAssertEqual(both?.result?.netSavingGBP ?? 0, -0.168911, accuracy: 1e-6)
+        XCTAssertEqual(both?.result?.netSavingGBP ?? 0, -0.166869, accuracy: 1e-6)
     }
 
     func testMixedRouteBasisIsReportedAsAnEstimate() {
@@ -393,7 +459,7 @@ final class FuelSavingsCalculationAuditTests: XCTestCase {
         XCTAssertEqual(mixed?.result?.distanceBasis, .straightLine,
                        "one unmeasured leg makes the whole estimate an estimate")
         XCTAssertEqual(mixed?.result?.journeyConfidence, .estimated)
-        XCTAssertEqual(mixed?.result?.headline(compact: true), "Approx. £0.17 worse off after travel")
+        XCTAssertEqual(mixed?.result?.headline(compact: true), "Approx. Costs £0.17 more")
     }
 
     func testBaselineStationIsLabelledClosestStationNotBreakEven() {

FuelBoardTests/Tests/FuelBoardSharedTests/FuelSavingsEstimateTests.swift

@@ -284,9 +284,9 @@ final class FuelSavingsEstimateTests: XCTestCase {
     /// (171.9p, 0.4 mi), candidate Shell Whetley Hill (167.9p, 3.8 mi).
     ///
     /// Whetley Hill is 4p/litre cheaper, yet it is WORSE OFF — and that is
-    /// correct, not a calculation bug: £60 buys 34.90 L at 171.9p, so the
+    /// correct, not a calculation bug: £60 buys 35.74 L at 167.9p, so the
-    /// cheaper pump saves 34.90 × 4p = £1.40, while the extra 6.8 return miles
+    /// cheaper pump saves 35.74 × 4p = £1.43, while the extra 6.8 return miles
-    /// burn 6.8/30 × 4.54609 = 1.03 L at 167.9p = £1.73. Net ≈ −£0.33.
+    /// burn 6.8/30 × 4.54609 = 1.03 L at 167.9p = £1.73. Net ≈ −£0.30.
     func testCheaperStationFurtherAwayIsWorseOffAfterTravel() {
         let baseline = station("rontec-shelf", price: 171.9)
         let candidate = station("shell-whetley-hill", price: 167.9)
@@ -304,16 +304,16 @@ final class FuelSavingsEstimateTests: XCTestCase {
         guard let result = availability?.result else {
             return XCTFail("expected an estimate, got \(String(describing: availability))")
         }
-        XCTAssertEqual(result.fillLitres, 34.904, accuracy: 0.005,
+        XCTAssertEqual(result.fillLitres, 35.736, accuracy: 0.005,
-                       "the £60 budget buys litres at the BASELINE pump price")
+                       "the £60 budget buys litres at the candidate pump price")
-        XCTAssertEqual(result.grossSavingGBP, 1.396, accuracy: 0.005)
+        XCTAssertEqual(result.grossSavingGBP, 1.429, accuracy: 0.005)
         XCTAssertEqual(result.extraDistanceMiles, 6.8, accuracy: 0.001,
                        "only the return-trip DELTA counts — the shared journey is never counted twice")
         XCTAssertEqual(result.extraDrivingCostGBP, 1.730, accuracy: 0.005)
-        XCTAssertEqual(result.netSavingGBP, -0.334, accuracy: 0.005)
+        XCTAssertEqual(result.netSavingGBP, -0.301, accuracy: 0.005)
         XCTAssertEqual(result.status, .notWorthTheDrive)
         XCTAssertEqual(result.journeyConfidence, .estimated)
-        XCTAssertEqual(result.headline(compact: true), "Approx. £0.33 worse off after travel")
+        XCTAssertEqual(result.headline(compact: true), "Approx. Costs £0.30 more")
     }
 
     func testMeasuredRoadRoutesDropTheEstimateMarker() {
@@ -332,8 +332,8 @@ final class FuelSavingsEstimateTests: XCTestCase {
 
         XCTAssertEqual(availability?.result?.distanceBasis, .roadRoute)
         XCTAssertEqual(availability?.result?.journeyConfidence, .confirmed)
-        XCTAssertEqual(availability?.result?.headline(compact: true), "£0.33 worse off after travel")
+        XCTAssertEqual(availability?.result?.headline(compact: true), "Costs £0.30 more")
-        XCTAssertEqual(availability?.result?.headline(), "£0.33 worse off after travel")
+        XCTAssertEqual(availability?.result?.headline(), "Costs £0.30 more")
     }
 
     func testBaselineRowIsLabelledClosestStation() {
@@ -375,10 +375,10 @@ final class FuelSavingsEstimateTests: XCTestCase {
             return XCTFail("expected an estimate, got \(String(describing: availability))")
         }
         XCTAssertEqual(result.status, .worthTheDrive)
-        // £60 buys 37.5 L at 160p; 10p/litre cheaper saves £3.75; 0.4 extra
+        // £60 buys 40 L at 150p; 10p/litre cheaper saves £4.00; 0.4 extra
-        // return miles cost ~£0.09. Net ≈ £3.66.
+        // return miles cost ~£0.09. Net ≈ £3.91.
-        XCTAssertEqual(result.netSavingGBP, 3.659, accuracy: 0.005)
+        XCTAssertEqual(result.netSavingGBP, 3.909, accuracy: 0.005)
-        XCTAssertEqual(result.headline(compact: true), "Approx. £3.66 better off after travel")
+        XCTAssertEqual(result.headline(compact: true), "Approx. Save £3.91")
     }
 
     func testNeutralResultHeadlineIsBreakEven() {
@@ -413,7 +413,7 @@ final class FuelSavingsEstimateTests: XCTestCase {
                                        netSavingGBP: 0.52,
                                        status: .worthTheDrive,
                                        distanceBasis: .roadRoute)
-        XCTAssertEqual(saving.headline(), "£0.52 better off after travel")
+        XCTAssertEqual(saving.headline(), "Save £0.52")
 
         let loss = FuelSavingsResult(fillLitres: 34.9,
                                      grossSavingGBP: 1.40,
@@ -422,7 +422,7 @@ final class FuelSavingsEstimateTests: XCTestCase {
                                      netSavingGBP: -0.31,
                                      status: .notWorthTheDrive,
                                      distanceBasis: .roadRoute)
-        XCTAssertEqual(loss.headline(), "£0.31 worse off after travel")
+        XCTAssertEqual(loss.headline(), "Costs £0.31 more")
     }
 
     /// The sort must order by NET saving, not pump price: a pricier station can
@@ -497,7 +497,7 @@ final class FuelSavingsEstimateTests: XCTestCase {
             status: .worthTheDrive,
             distanceBasis: .straightLine
         )
-        XCTAssertEqual(saving.capsuleHeadline(), "Approx. £1.00 better off after travel")
+        XCTAssertEqual(saving.capsuleHeadline(), "Approx. Save £1.00")
 
         let worse = FuelSavingsResult(
             fillLitres: 30,
@@ -507,7 +507,7 @@ final class FuelSavingsEstimateTests: XCTestCase {
             netSavingGBP: -0.31,
             status: .notWorthTheDrive
         )
-        XCTAssertEqual(worse.capsuleHeadline(), "£0.31 worse off after travel")
+        XCTAssertEqual(worse.capsuleHeadline(), "Costs £0.31 more")
     }
 
     // MARK: - Estimate wording (Approx. labels)
@@ -524,7 +524,7 @@ final class FuelSavingsEstimateTests: XCTestCase {
             status: .worthTheDrive,
             distanceBasis: .straightLine
         )
-        XCTAssertEqual(saving.headline(), "Approx. £1.25 better off after travel")
+        XCTAssertEqual(saving.headline(), "Approx. Save £1.25")
 
         let loss = FuelSavingsResult(
             fillLitres: 30,
@@ -535,7 +535,7 @@ final class FuelSavingsEstimateTests: XCTestCase {
             status: .notWorthTheDrive,
             distanceBasis: .straightLine
         )
-        XCTAssertEqual(loss.headline(), "Approx. £0.77 worse off after travel")
+        XCTAssertEqual(loss.headline(), "Approx. Costs £0.77 more")
     }
 
     /// A confirmed road-route comparison must never carry the marker — in either
@@ -551,7 +551,7 @@ final class FuelSavingsEstimateTests: XCTestCase {
             distanceBasis: .roadRoute,
             journeyConfidence: .confirmed
         )
-        XCTAssertEqual(saving.headline(), "£1.25 better off after travel")
+        XCTAssertEqual(saving.headline(), "Save £1.25")
 
         let loss = FuelSavingsResult(
             fillLitres: 30,
@@ -563,7 +563,7 @@ final class FuelSavingsEstimateTests: XCTestCase {
             distanceBasis: .roadRoute,
             journeyConfidence: .confirmed
         )
-        XCTAssertEqual(loss.headline(), "£0.77 worse off after travel")
+        XCTAssertEqual(loss.headline(), "Costs £0.77 more")
 
         for headline in [saving.headline(), loss.headline(), saving.capsuleHeadline()] {
             XCTAssertFalse(headline.contains("Approx"), "\"\(headline)\" must not claim to be an estimate")
@@ -597,7 +597,7 @@ final class FuelSavingsEstimateTests: XCTestCase {
             status: .notWorthTheDrive,
             distanceBasis: .straightLine
         )
-        XCTAssertEqual(estimated.spokenHeadline(), "Approximately £0.77 worse off after travel")
+        XCTAssertEqual(estimated.spokenHeadline(), "Approximately Costs £0.77 more")
 
         XCTAssertEqual(
             FuelSavingsFormat.extraTravelSpokenLabel(extraDistanceMiles: 6.4, unit: .miles, confidence: .estimated),

FuelBoardTests/Tests/FuelBoardSharedTests/FuelSavingsTests.swift

@@ -8,15 +8,15 @@ final class FuelSavingsCalculatorTests: XCTestCase {
         XCTAssertEqual(FuelSavingsCalculator.fuelUsedLitres(distanceMiles: 10, mpg: 45), 1.0102, accuracy: 0.0001)
     }
 
-    func testPoundsBudgetConvertsToLitresUsingBaselinePrice() throws {
+    func testPoundsBudgetConvertsToLitresUsingGivenPrice() throws {
         let amount = FuelSavingsFillAmount(value: 40, unit: .pounds)
-        let litres = try FuelSavingsCalculator.fillLitres(amount: amount, baselinePricePencePerLitre: 160)
+        let litres = try FuelSavingsCalculator.fillLitres(amount: amount, pricePencePerLitre: 160)
         XCTAssertEqual(litres, 25.0, accuracy: 0.0001)
     }
 
     func testLitresAmountPassesThrough() throws {
         let amount = FuelSavingsFillAmount(value: 35, unit: .litres)
-        let litres = try FuelSavingsCalculator.fillLitres(amount: amount, baselinePricePencePerLitre: 160)
+        let litres = try FuelSavingsCalculator.fillLitres(amount: amount, pricePencePerLitre: 160)
         XCTAssertEqual(litres, 35, accuracy: 0.0001)
     }
 
@@ -29,11 +29,11 @@ final class FuelSavingsCalculatorTests: XCTestCase {
             baselineJourneyMiles: 2,
             candidateJourneyMiles: 8
         )
-        XCTAssertEqual(result.fillLitres, 25, accuracy: 0.0001)
+        XCTAssertEqual(result.fillLitres, 26.6667, accuracy: 0.0001)
-        XCTAssertEqual(result.grossSavingGBP, 2.50, accuracy: 0.0001)
+        XCTAssertEqual(result.grossSavingGBP, 2.6667, accuracy: 0.0001)
         XCTAssertEqual(result.extraDistanceMiles, 6, accuracy: 0.0001)
         XCTAssertEqual(result.extraDrivingCostGBP, 0.9092, accuracy: 0.0001)
-        XCTAssertEqual(result.netSavingGBP, 1.5908, accuracy: 0.0001)
+        XCTAssertEqual(result.netSavingGBP, 1.7574, accuracy: 0.0001)
         XCTAssertEqual(result.status, .worthTheDrive)
     }
 
@@ -61,7 +61,7 @@ final class FuelSavingsCalculatorTests: XCTestCase {
     }
 
     func testInvalidInputsRejected() {
-        XCTAssertThrowsError(try FuelSavingsCalculator.fillLitres(amount: FuelSavingsFillAmount(value: 40, unit: .pounds), baselinePricePencePerLitre: 0))
+        XCTAssertThrowsError(try FuelSavingsCalculator.fillLitres(amount: FuelSavingsFillAmount(value: 40, unit: .pounds), pricePencePerLitre: 0))
         XCTAssertThrowsError(try FuelSavingsCalculator.calculate(mpg: 0, amount: FuelSavingsFillAmount(value: 40, unit: .pounds), baselinePricePencePerLitre: 160, candidatePricePencePerLitre: 150, baselineJourneyMiles: 1, candidateJourneyMiles: 2))
         XCTAssertThrowsError(try FuelSavingsCalculator.calculate(mpg: 500, amount: FuelSavingsFillAmount(value: 40, unit: .pounds), baselinePricePencePerLitre: 160, candidatePricePencePerLitre: 150, baselineJourneyMiles: 1, candidateJourneyMiles: 2))
     }

Shared/FuelSavings.swift

@@ -82,6 +82,7 @@ enum JourneyConfidence: String, Codable, Equatable {
 struct FuelSavingsResult: Codable, Equatable {
     let fillLitres: Double
     let grossSavingGBP: Double
+    let extraFuelLitres: Double
     let extraDrivingCostGBP: Double
     let extraDistanceMiles: Double
     let netSavingGBP: Double
@@ -91,6 +92,7 @@ struct FuelSavingsResult: Codable, Equatable {
 
     init(fillLitres: Double,
          grossSavingGBP: Double,
+         extraFuelLitres: Double = 0,
          extraDrivingCostGBP: Double,
          extraDistanceMiles: Double,
          netSavingGBP: Double,
@@ -99,6 +101,7 @@ struct FuelSavingsResult: Codable, Equatable {
          journeyConfidence: JourneyConfidence? = nil) {
         self.fillLitres = fillLitres
         self.grossSavingGBP = grossSavingGBP
+        self.extraFuelLitres = extraFuelLitres
         self.extraDrivingCostGBP = extraDrivingCostGBP
         self.extraDistanceMiles = extraDistanceMiles
         self.netSavingGBP = netSavingGBP
@@ -174,6 +177,7 @@ extension FuelSavingsResult {
         FuelSavingsResult(
             fillLitres: fillLitres,
             grossSavingGBP: 0,
+            extraFuelLitres: 0,
             extraDrivingCostGBP: 0,
             extraDistanceMiles: 0,
             netSavingGBP: 0,
@@ -199,9 +203,9 @@ extension FuelSavingsResult {
         case .breakEven:
             return Self.breakEvenHeadline
         case .worthTheDrive:
-            return "\(prefix)\(FuelSavingsFormat.money(netSavingGBP)) better off after travel"
+            return "\(prefix)Save \(FuelSavingsFormat.money(netSavingGBP))"
         case .notWorthTheDrive:
-            return "\(prefix)\(FuelSavingsFormat.money(abs(netSavingGBP))) worse off after travel"
+            return "\(prefix)Costs \(FuelSavingsFormat.money(abs(netSavingGBP))) more"
         }
     }
 
@@ -321,16 +325,16 @@ enum FuelSavingsCalculator {
         distanceMiles / mpg * imperialGallonLitres
     }
 
-    static func fillLitres(amount: FuelSavingsFillAmount, baselinePricePencePerLitre: Double) throws -> Double {
+    static func fillLitres(amount: FuelSavingsFillAmount, pricePencePerLitre: Double) throws -> Double {
         guard amount.isValid else { throw FuelSavingsError.invalidAmount }
         switch amount.unit {
         case .litres:
             return amount.value
         case .pounds:
-            guard baselinePricePencePerLitre.isFinite, baselinePricePencePerLitre > 0 else {
+            guard pricePencePerLitre.isFinite, pricePencePerLitre > 0 else {
                 throw FuelSavingsError.invalidPrice
             }
-            return amount.value / (baselinePricePencePerLitre / 100.0)
+            return amount.value / (pricePencePerLitre / 100.0)
         }
     }
 
@@ -376,7 +380,7 @@ enum FuelSavingsCalculator {
               baselineJourneyMiles >= 0, candidateJourneyMiles >= 0 else {
             throw FuelSavingsError.invalidDistance
         }
-        let fillLitres = try fillLitres(amount: amount, baselinePricePencePerLitre: baselinePricePencePerLitre)
+        let fillLitres = try fillLitres(amount: amount, pricePencePerLitre: candidatePricePencePerLitre)
         let baselinePriceGBP = baselinePricePencePerLitre / 100.0
         let candidatePriceGBP = candidatePricePencePerLitre / 100.0
         let grossSaving = fillLitres * (baselinePriceGBP - candidatePriceGBP)
@@ -395,6 +399,7 @@ enum FuelSavingsCalculator {
         return FuelSavingsResult(
             fillLitres: fillLitres,
             grossSavingGBP: grossSaving,
+            extraFuelLitres: extraFuelLitres,
             extraDrivingCostGBP: extraFuelCost,
             extraDistanceMiles: extraDistance,
             netSavingGBP: netSaving,