MPG vs. L/100km: Understanding Fuel Efficiency

In the US, we want a HIGH number for fuel efficiency (30 MPG is better than 20 MPG). In Europe and Canada, they want a LOW number (5 L/100km is better than 8 L/100km).

The Difference

MPG (Miles Per Gallon): Measures distance per unit of fuel.

L/100km (Liters per 100 Kilometers): Measures fuel consumption over a fixed distance.

The US Gallon vs UK Gallon

To make matters worse, the UK uses MPG, but their gallon is 20% larger than the US gallon! So a car rated at "50 MPG" in the UK would only be rated at about "41 MPG" in the US. Keep this in mind when reading car reviews from British magazines.