MPG
calculator
Fill the tank, reset the trip meter, drive, fill again: miles divided by gallons is your car's honest fuel economy. Plus the metric translations the rest of the world uses.
Measuring it properly
The tank-to-tank method beats any dashboard readout: fill completely, reset the trip odometer, drive normally, fill completely again. Miles on the trip divided by gallons on the second receipt is your true economy — dashboards commonly flatter by 5–10%.
Why L/100km runs backwards
MPG measures distance per fuel (higher = better); L/100km measures fuel per distance (lower = better). The inversion matters: going from 12→15 MPG saves more fuel per year than 30→40, even though the second jump sounds bigger — the "MPG illusion" that L/100km avoids. Note UK gallons are 20% larger, so UK MPG figures read higher for the same car.
Feed your real number into the fuel cost calculator and trip budgets get honest.
MPG FAQ
Fill the tank, reset the trip meter, drive, then fill again. Miles driven divided by gallons at the second fill is your real MPG — more honest than the dashboard estimate.
Divide 235.215 by the MPG. 30 MPG is 7.8 L/100km; remember the scales run in opposite directions — lower L/100km is better.
The imperial gallon is 4.546 liters versus the US 3.785 — about 20% bigger — so the same car scores roughly 20% more UK MPG.
For gas cars: under 20 is thirsty, around 25–30 typical, 35+ efficient, and 45–55+ is hybrid territory. Driving style swings any car's figure by 10–20%.