Liters per km to Miles per gallon (UK)
L/km
mpg
Conversion History
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Quick Reference Table (Liters per km to Miles per gallon (UK))
| Liters per km (L/km) | Miles per gallon (UK) (mpg) |
|---|---|
| 0.04 | 70.62023407 |
| 0.06 | 47.08015604666666666667 |
| 0.07 | 40.35441946857142857143 |
| 0.08 | 35.310117035 |
| 0.1 | 28.248093628 |
| 0.12 | 23.54007802333333333333 |
| 0.15 | 18.83206241866666666667 |
About Liters per km (L/km)
Liters per kilometer (L/km) is the most granular metric fuel consumption unit, expressing the volume of fuel burned for every individual kilometer driven. Because a typical passenger car consumes only 0.04–0.15 L/km, the number is inconveniently small for everyday use, and most metric markets prefer L/10km or L/100km. L/km is used in engineering calculations, telematics data streams, and as the mathematical base for converting between metric consumption and efficiency units. It is the direct reciprocal of km/L: a car using 0.07 L/km travels approximately 14.3 km per liter.
A compact car rated at 7 L/100km consumes 0.07 L/km. A large SUV at 12 L/100km uses 0.12 L/km — visible as a small daily difference that compounds significantly over tens of thousands of kilometers.
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.
Liters per km – Frequently Asked Questions
Why do engineers use L/km instead of L/100km?
L/km is the raw mathematical unit that telematics systems and engine control units log internally. It maps directly to instantaneous fuel flow divided by speed, making it ideal for real-time calculations. Multiplying by 100 to get L/100km is a display convenience for humans, not a computing necessity.
How do fleet telematics systems use L/km data to coach drivers in real time?
Modern telematics units sample fuel flow and GPS speed several times per second, computing instantaneous L/km continuously. When the value spikes — hard acceleration, excessive idling, speeding — the system triggers an in-cab alert or scores the behavior for later review. Over thousands of vehicles, coaching drivers to shave even 0.005 L/km off their average can save a fleet millions of liters per year.
What L/km does a Formula 1 car use during a race?
An F1 car burns roughly 0.35–0.45 L/km under race conditions, about five times more than a typical passenger car. FIA regulations cap total fuel at 110 kg per race, forcing teams to balance speed against consumption strategically.
Is 0.05 L/km considered fuel-efficient for a modern car?
Yes, 0.05 L/km (equivalent to 5 L/100km or ~47 US mpg) is quite efficient. Most petrol hybrids achieve this range. A non-hybrid petrol car would need to be a well-optimized compact to hit that mark consistently in mixed driving.
Why does my OBD scanner show fuel rate in L/km not L/100km?
OBD-II standardized on raw per-kilometer (or per-mile) metrics because the ECU calculates consumption at the granular level. Your dashboard or app multiplies by 100 for display. The raw L/km reading updates in real time and is more useful for diagnosing injector performance or driving behavior.
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.