I'm importing a car from Japan rated 18 km/L. How does that compare to UK fuel economy figures I've seen in car reviews?

18 × 2.824809 = 50.8 mpg (Imperial). That's excellent by UK standards — most petrol family cars achieve 40–55 mpg (Imperial) on the official combined cycle. Your import would be competitive with an efficient diesel or mild hybrid.

Why is mpg (Imperial) higher than mpg (US) for the same vehicle?

The Imperial gallon is larger (4.546 L vs 3.785 L). A car travelling the same distance uses fewer Imperial gallons than US gallons, so the mpg (Imperial) number is always about 20% higher. Never compare mpg (Imperial) to mpg (US) directly without converting. See: [km/L to mpg (US)](/fuel/kml-to-mpg/).

My South Korean car's spec sheet shows 16 km/L under WLTC conditions. What will I realistically get in UK driving?

16 km/L × 2.824809 = 45.2 mpg (Imperial) under WLTC. In real-world UK driving, expect 10–20% less than official figures, so around 38–42 mpg (Imperial). Urban driving with cold starts will push it lower; steady motorway cruising will be close to the official figure.

Is km/L used in any right-hand-drive markets where I'd want to compare to UK figures directly?

Yes — Japan, South Korea, India, Malaysia, and several other right-hand-drive markets use km/L as the official or dominant fuel economy unit. When comparing vehicles across these markets with the UK, this converter gives you the Imperial mpg figure used in UK road tests and insurance records.

km/L to MPG (Imperial) Converter

Enter a value to instantly convert between fuel economy units.

From

Precision4 dp

1 Km per Liter = 2.8248 MPG (Imperial)

Key Formulas

MPG (US) → Liters per 100km

L/100km = mpg × 235.215

Liters per 100km → MPG (US)

mpg = L/100km × 235.215

Km per Liter → MPG (US)

mpg = km/L × 2.35215

MPG (US) → Km per Liter

km/L = mpg × 0.425144

Formula

mpg (Imperial) = km/L × 2.824809

Importing a Japanese or Korean car to the UK, or comparing spec sheets across two continents? Asian manufacturers rate vehicles in kilometers per liter, while the UK uses miles per Imperial gallon — the larger of the two gallon definitions. Because the Imperial gallon holds 4.546 litres (20% more than the US gallon), mpg (Imperial) figures come out about 20% higher than mpg (US) for the same car. Multiplying km/L by 2.825 gives the Imperial mpg equivalent, letting you place the Asian vehicle in context against What Car? or Autocar fuel economy figures.

Source: NIST SP 811, Table B.8

Last reviewed: 2026-06-11 · see our methodology

Frequently Asked Questions

Real-World Examples

A typical Japanese market compact car at 15 km/L converts to 42.4 mpg (Imperial) — solid mid-range economy by UK standards for a petrol hatchback.

15 km/L = 42.4 mpg imp

A mid-size Japanese sedan at 10 km/L delivers 28.2 mpg (Imperial), roughly average for a UK family saloon on the old NEDC test cycle.

10 km/L = 28.2 mpg imp

A Japanese hybrid at 20 km/L achieves 56.5 mpg (Imperial) — comparable to UK official economy figures for hybrids like the Toyota Yaris.

20 km/L = 56.5 mpg imp

A larger Japanese 4WD rated 7 km/L equals 19.8 mpg (Imperial), typical for heavier utility vehicles in the UK market.

7 km/L = 19.8 mpg imp

mpg to l per 100km l per 100km to mpg kml to mpg mpg to kml

km/L to MPG (Imperial) Converter

Key Formulas

Formula

Frequently Asked Questions

Real-World Examples

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