Miles per gallon (UK) to Liters per 10 km
mpg
L/10km
Conversion History
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Quick Reference Table (Miles per gallon (UK) to Liters per 10 km)
| Miles per gallon (UK) (mpg) | Liters per 10 km (L/10km) |
|---|---|
| 20 | 1.4124046814 |
| 30 | 0.9416031209333333333 |
| 40 | 0.7062023407 |
| 50 | 0.56496187256 |
| 55 | 0.5136017023272727273 |
| 60 | 0.4708015604666666667 |
| 70 | 0.4035441946857142857 |
About Miles per gallon (UK) (mpg)
Miles per gallon (imperial) — also written UK mpg — is the traditional British fuel economy unit, using the imperial gallon of 4.546 liters rather than the smaller US gallon (3.785 L). Because the imperial gallon is approximately 20% larger, UK mpg figures are roughly 20% higher than US mpg for the same vehicle: a car rated at 40 US mpg is approximately 48 UK mpg. The UK officially adopted L/100km for type-approval testing under EU harmonisation, but UK mpg remains prevalent in British automotive journalism, used-car listings, and consumer conversations in the United Kingdom and Ireland.
A typical family hatchback in the UK achieves 45–55 mpg (imperial) on the WLTP combined cycle. A 60 UK mpg rating equates to approximately 50 US mpg or 4.7 L/100km.
About Liters per 10 km (L/10km)
Liters per 10 kilometers (L/10km) is a mid-scale fuel consumption unit used primarily in Japan and some East Asian markets as a more readable alternative to L/km. A typical Japanese passenger car achieves 0.6–0.8 L/10km, presenting numbers in a familiar single-digit range. The unit appears on Japanese fuel economy test results and in Asian automotive media. It is exactly one-tenth of the L/100km figure: a European rating of 7 L/100km equals 0.7 L/10km. The unit avoids the leading zeros of L/km while remaining more precise than L/100km for shorter reference distances.
A fuel-efficient kei car achieves around 0.4–0.5 L/10km. A standard Japanese family sedan typically rates at 0.7–0.8 L/10km on the JC08 test cycle.
Miles per gallon (UK) – Frequently Asked Questions
Why is UK mpg different from US mpg for the same car?
The imperial gallon (4.546 L) is 20.1% larger than the US gallon (3.785 L). So a car that travels 40 miles on a US gallon would travel 40 miles on less than one imperial gallon, yielding a higher UK mpg number. Same car, same fuel, different gallon definitions — endlessly confusing.
Is UK mpg still used now that Britain uses liters at the pump?
Yes, stubbornly so. British fuel is sold in liters and road signs show miles, but most Brits still discuss fuel economy in mpg (imperial). It is a quirky holdover — they buy liters, drive miles, and mentally calculate in a unit that directly matches neither.
How do I convert UK mpg to L/100km?
Divide 282.5 by the UK mpg value. So 50 UK mpg equals 282.5 ÷ 50 = 5.65 L/100km. For US mpg, divide 235.2 instead. These magic numbers are worth memorising if you cross-shop cars between markets.
Why did UK diesel car sales collapse after 2017 despite their higher mpg?
The Volkswagen emissions scandal (2015) shattered public trust in diesel. The UK government then announced clean-air zones charging diesel cars extra, raised vehicle excise duty on new diesels, and signalled a 2030 petrol/diesel ban. Residual values cratered, making diesel a bad financial bet despite 15–20% better mpg. Diesel's UK market share fell from 48% in 2015 to under 10% by 2023, replaced by hybrids and EVs.
Why do British car magazines show different mpg than the manufacturer claims?
Manufacturers quote official WLTP lab test results, while magazines run real-world tests with varying conditions. Magazine figures are usually 10–20% worse than WLTP because they include cold starts, traffic, motorway speeds above test assumptions, and actual British weather.
Liters per 10 km – Frequently Asked Questions
Why does Japan use L/10km instead of L/100km like Europe?
Japan traditionally used km/L as its primary fuel economy metric, and L/10km emerged as a convenient consumption-based complement at a scale that keeps numbers in a comfortable single-digit range for Japanese commuting distances. European L/100km values feel oversized for Japan, where average daily drives are shorter.
Why are Japanese highway speed limits lower and how does that affect fuel figures?
Most Japanese expressways cap at 100–120 km/h, well below the 130 km/h common in Europe or the 120+ km/h effective speed on US interstates. Aerodynamic drag rises with the square of speed, so Japan's lower cruising speeds significantly reduce fuel consumption at highway pace. This is one reason Japanese test-cycle numbers look so good — the driving profile genuinely reflects slower, more fuel-friendly conditions.
What is a good L/10km figure for a kei car?
A modern kei car (660cc engine) typically achieves 0.4–0.55 L/10km, equivalent to 4–5.5 L/100km. The Suzuki Alto has historically been one of the best performers, dipping below 0.4 L/10km on the lenient JC08 test cycle.
Is L/10km used on Japanese fuel economy stickers?
Not directly — Japanese window stickers display km/L as the primary metric. However, L/10km appears in some technical publications and comparison tools because it bridges the gap between the Japanese km/L convention and the European L/100km standard.
How does the JC08 test cycle compare to WLTP for L/10km ratings?
JC08 results are typically 10–20% more optimistic than WLTP because JC08 uses lower speeds and gentler acceleration profiles. A car rated 0.5 L/10km on JC08 might realistically achieve 0.6 L/10km on the more demanding WLTP cycle.