diff --git a/client/src/components/Roadtrip/vehicleRange.test.ts b/client/src/components/Roadtrip/vehicleRange.test.ts
index 9e5cf4f01..eaabec5e1 100644
--- a/client/src/components/Roadtrip/vehicleRange.test.ts
+++ b/client/src/components/Roadtrip/vehicleRange.test.ts
@@ -105,6 +105,22 @@ describe('unit round trip', () => {
     expect(showSpec('batteryKwh', 58, true)).toBe(58)
   })
 
+  it('FE-ROADTRIP-VEHRANGE-016: a consumption typed a hundred times too high does not silence the typed range', () => {
+    // A consumption of 500 rather than 5.0 makes the parts round to nothing. Zero used
+    // to count as an answer, so the `??` in effectiveRangeKm never reached the 500 km
+    // the traveller had typed by hand, and every range warning went quiet with nothing
+    // on screen to say which field did it.
+    expect(rangeFromSpec('combustion', { tankLitres: 1, litresPer100: 500 })).toBeNull()
+    expect(effectiveRangeKm('combustion', { tankLitres: 1, litresPer100: 500 }, 500)).toBe(500)
+
+    // Same shape on the other kind of car, where a decimal point is just as easy to lose.
+    expect(rangeFromSpec('electric', { batteryKwh: 0.5, kwhPer100: 200 })).toBeNull()
+    expect(effectiveRangeKm('electric', { batteryKwh: 0.5, kwhPer100: 200 }, 420)).toBe(420)
+
+    // One kilometre is still a figure, so the cut is below it and not at some round guess.
+    expect(rangeFromSpec('combustion', { tankLitres: 1, litresPer100: 100 })).toBe(1)
+  })
+
   it('FE-ROADTRIP-VEHRANGE-015: an empty field stays empty rather than becoming a zero', () => {
     expect(showSpec('tankLitres', undefined, false)).toBeUndefined()
     expect(showSpec('tankLitres', 0, true)).toBeUndefined()
diff --git a/client/src/components/Roadtrip/vehicleRange.ts b/client/src/components/Roadtrip/vehicleRange.ts
index 44532e47c..cda588664 100644
--- a/client/src/components/Roadtrip/vehicleRange.ts
+++ b/client/src/components/Roadtrip/vehicleRange.ts
@@ -46,12 +46,25 @@ function positive(value: number | null | undefined): number | null {
  * Null rather than a guess whenever a piece is missing: half a specification is not a
  * range, and a made-up figure here becomes a fuel warning that fires at the wrong place.
  */
+/**
+ * A rounded range that came out at nothing is a typo, not a car.
+ *
+ * A consumption typed as 500 rather than 5.0 rounds to a range of zero, and zero is a
+ * number: `effectiveRangeKm` would take it as the answer and throw away the range the
+ * traveller had typed by hand right next to it. What reached the rail was "no range at
+ * all", so every warning went quiet, with nothing on screen to say which field did it.
+ * Reported as nothing instead, so the typed figure gets its turn.
+ */
+function atLeastAKilometre(km: number): number | null {
+  return km >= 1 ? km : null
+}
+
 export function rangeFromSpec(vehicle: VehicleKind | null | undefined, spec: VehicleSpec): number | null {
   if (vehicle === 'combustion') {
     const tank = positive(spec.tankLitres)
     const per100 = positive(spec.litresPer100)
     if (!tank || !per100) return null
-    return Math.round((tank / per100) * 100)
+    return atLeastAKilometre(Math.round((tank / per100) * 100))
   }
 
   if (vehicle === 'electric') {
@@ -63,7 +76,7 @@ export function rangeFromSpec(vehicle: VehicleKind | null | undefined, spec: Veh
     // the first metre of the trip.
     const lost = Math.min(90, Math.max(0, positive(spec.degradationPercent) ?? 0))
     const usable = battery * (1 - lost / 100)
-    return Math.round((usable / per100) * 100)
+    return atLeastAKilometre(Math.round((usable / per100) * 100))
   }
 
   return null