Understanding Fuel Economy Units
Different countries use different units to measure fuel economy. The United States uses miles per gallon (MPG), the UK uses imperial MPG (which is about 20% higher than US MPG due to the larger imperial gallon), and most of the world uses liters per 100 kilometers (L/100km) or kilometers per liter (km/L).
Understanding these conversions is essential when comparing vehicles from different markets, reading international reviews, or traveling abroad where fuel pump displays use different metrics.
Conversion Formulas
Fuel Economy Conversion Table
| MPG (US) | MPG (UK) | L/100km | km/L |
|---|---|---|---|
| 20 | 24.0 | 11.76 | 8.50 |
| 25 | 30.0 | 9.41 | 10.63 |
| 30 | 36.0 | 7.84 | 12.75 |
| 35 | 42.0 | 6.72 | 14.88 |
| 40 | 48.0 | 5.88 | 17.01 |
| 50 | 60.0 | 4.70 | 21.26 |
Frequently Asked Questions
Why is UK MPG higher than US MPG?
The imperial gallon (UK) is about 20% larger than the US gallon (3.785 L vs. 4.546 L). So the same car traveling the same distance will have a higher MPG number in UK units because imperial gallons are bigger.
Is L/100km better than MPG?
L/100km is actually a more linear and intuitive measure for comparing fuel savings. In MPG, the difference between 10 and 20 MPG saves more fuel than the difference between 30 and 40 MPG, which can be misleading. L/100km avoids this problem.
What is a good L/100km rating?
Below 6 L/100km is considered efficient, 6-8 L/100km is average for a car, 8-12 L/100km is typical for SUVs, and above 12 L/100km indicates a heavy or performance vehicle.