Work out mileage (km/l) instantly with clear inputs, formula shown and shareable results.
The brim-to-brim method is the reliable way to measure mileage: fill the tank, note the odometer, drive, then refill completely and divide distance by the fuel added. Both fills must be to the same point for the answer to mean anything.
Mileage
km/L = (end odometer - start odometer) / litres added
On-board computers estimate from injector timing and are commonly 3-8% optimistic. Brim-to-brim over several tanks is the honest figure.
Fill-level variation adds noise to a single measurement. Averaging three or four tanks gives a figure accurate to a couple of percent.