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How efficiency is measured
Between consecutive full fill-ups, and never averaged through a gap.
Where: Vehicle ▸ Fuel & trips (or Charging & trips)
Efficiency is measured between consecutive full, non-missed fill-ups of the same kind, using the odometer reading on each. A partial fill or a missed one breaks the chain honestly rather than averaging through it.
A plug-in hybrid keeps two independent chains, fuel and charge. An electric vehicle shows distance per kWh from its charges in the same way.
If a vehicle's efficiency drops well below its own recent average, paid plans send an efficiency alert so a dragging brake or a soft tire gets noticed early.