Miles per gallon (US) to Miles per gallon (UK)
mpg
mpg
Conversion History
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Quick Reference Table (Miles per gallon (US) to Miles per gallon (UK))
| Miles per gallon (US) (mpg) | Miles per gallon (UK) (mpg) |
|---|---|
| 15 | 18.01424888258679022525 |
| 20 | 24.01899851011572029982 |
| 25 | 30.02374813764465037477 |
| 30 | 36.0284977651735804482 |
| 40 | 48.03799702023144059964 |
| 50 | 60.04749627528930074955 |
| 55 | 66.0522459028182308231 |
About Miles per gallon (US) (mpg)
Miles per gallon (US) — universally abbreviated mpg in the United States — is the dominant fuel economy metric in American automotive culture. Higher mpg means lower fuel consumption. The US gallon is 3.785 liters. The US Environmental Protection Agency (EPA) publishes city, highway, and combined mpg ratings on new vehicle window stickers, and Corporate Average Fuel Economy (CAFE) standards are set in mpg. Typical US passenger cars range from 15–20 mpg for trucks and large SUVs to 50–60 mpg for modern petrol hybrids. Because mpg is an efficiency unit (not consumption), the fuel savings from improving a low-mpg vehicle far exceed the savings from improving an already-efficient one.
A Ford F-150 pickup averages about 20 mpg combined on the EPA cycle. A Toyota Camry Hybrid achieves approximately 47 mpg combined.
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.
Miles per gallon (US) – Frequently Asked Questions
Why is EPA mpg always higher than what I actually get?
The EPA tests cars on a dynamometer in a lab, not on real roads. While EPA adjusted its formulas in 2008 to be more realistic, factors like cold weather, air conditioning, aggressive driving, hilly terrain, and short trips still cause most drivers to underperform the sticker by 10–20%.
Why does the US use miles per gallon instead of L/100km?
The US never adopted the metric system for everyday use, and mpg has been embedded in American car culture since the 1970s oil crisis when fuel economy became a selling point. CAFE standards codified mpg into federal law, making a switch politically and practically difficult.
What is the "mpg illusion" and why does it matter?
The mpg illusion is the cognitive bias where people assume equal mpg improvements save equal fuel. In reality, upgrading a truck from 12 to 14 mpg saves more gallons over 10,000 miles than upgrading a sedan from 30 to 50 mpg. This is because mpg is a reciprocal measure — savings are concentrated at the low end.
How do I convert US mpg to UK mpg?
Multiply US mpg by 1.201 to get UK mpg (because the imperial gallon is 20.1% larger than the US gallon). A car rated 30 US mpg is about 36 UK mpg. Many Americans visiting the UK are confused when British cars seem to get impossibly high mpg numbers.
What is the highest mpg car ever sold in the US?
The 2025 Hyundai Ioniq Blue held the record for non-plug-in cars at 59 mpg combined. Among hybrids, the Toyota Prius has consistently led, reaching 57 mpg combined in recent model years. Plug-in hybrids running on electricity achieve MPGe ratings over 100, but that is a different metric entirely.
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.