Fuel Efficiency Converter
Convert between UK MPG, US MPG, litres per 100km (L/100km), and km per litre — the four main fuel economy metrics.
How Fuel Efficiency Converter works
UK MPG vs L/100km
UK MPG uses the Imperial gallon (4.54609 litres). To convert: L/100km = 282.481 ÷ UK MPG. A typical UK petrol car achieves 35–50 mpg (5.6–8.1 L/100km).
UK MPG vs US MPG
The UK (Imperial) gallon is 20% larger than the US gallon. 1 UK MPG = 1.20095 US MPG. A car rated 40 UK MPG would be rated 33.3 US MPG.
L/100km interpretation
Lower L/100km means better fuel economy (less fuel per distance). Higher MPG means better fuel economy (more distance per fuel). The EU uses L/100km; UK car specs often show both.
Frequently asked questions
How do I convert MPG to L/100km?
For UK MPG: divide 282.481 by the MPG figure. Example: 40 UK MPG = 282.481 ÷ 40 = 7.06 L/100km.
What is the difference between UK and US MPG?
UK MPG uses the Imperial gallon (4.546 L); US MPG uses the US gallon (3.785 L). UK MPG figures are ~20% higher than US MPG for the same car.
What is a good MPG for a UK car?
Most petrol cars achieve 30–50 mpg. Diesel cars typically achieve 40–65 mpg. Hybrids can achieve 50–70+ mpg. Electric cars don't use MPG — their efficiency is measured in miles per kWh.
How do I convert L/100km to MPG?
UK MPG = 282.481 ÷ L/100km. Example: 6 L/100km = 282.481 ÷ 6 = 47.1 UK MPG.
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