Liters per 100 km to Gallons per 100 miles (UK)
L/100km
gal/100mi (UK)
Conversion History
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Quick Reference Table (Liters per 100 km to Gallons per 100 miles (UK))
| Liters per 100 km (L/100km) | Gallons per 100 miles (UK) (gal/100mi (UK)) |
|---|---|
| 4 | 885.01547489 |
| 6 | 590.010316593333333333451335396652 |
| 7 | 505.723128508571428571580288367124 |
| 8 | 442.507737445 |
| 10 | 354.006189956 |
| 12 | 295.005158296666666666548664603348 |
| 15 | 236.004126637333333333451335396652 |
About Liters per 100 km (L/100km)
Liters per 100 kilometers (L/100km) is the standard fuel consumption unit across the European Union, Australia, Canada, China, and most of the metric world. It expresses how many liters of fuel a vehicle burns to travel 100 km — a lower number indicates greater efficiency. Modern petrol passenger cars range from about 4 L/100km for efficient small cars to 15 L/100km or more for large SUVs and trucks. Because the unit measures consumption rather than efficiency, its relationship with km/L and mpg is non-linear: a change from 15 to 10 L/100km saves more fuel per kilometer than a change from 6 to 5 L/100km.
A Toyota Prius averages about 4.5 L/100km under EU testing. A full-size petrol SUV typically consumes 10–14 L/100km on the combined WLTP cycle.
About Gallons per 100 miles (UK) (gal/100mi (UK))
Gallons per 100 miles (imperial) is the British consumption-oriented counterpart to the metric L/100km standard, expressing how many imperial gallons a vehicle burns over 100 miles. It is numerically distinct from its US equivalent because the imperial gallon (4.546 L) is larger than the US gallon (3.785 L), so UK gal/100mi values are roughly 20% lower than US gal/100mi for identical fuel consumption. The unit is used in UK engineering and fleet management contexts where consumption rather than efficiency framing is preferred, and in academic analysis of British vehicle fuel-use data.
A 50 UK mpg car consumes 2 gal/100mi (imperial). A typical British family SUV at 35 UK mpg uses about 2.86 gal/100mi (imperial).
Liters per 100 km – Frequently Asked Questions
Does fuel consumption increase linearly with speed, or is there a sweet spot?
There is a sweet spot, typically between 50 and 80 km/h for most cars. Below that, the engine runs inefficiently at low load. Above it, aerodynamic drag — which scales with the square of speed — dominates. At 120 km/h a car may use 7 L/100km; at 160 km/h the same car could burn 11+ L/100km. That is why the jump from 100 to 130 km/h costs far more fuel than from 70 to 100.
What L/100km should I expect in real-world driving vs the WLTP sticker?
Most drivers see 10–25% higher consumption than the WLTP rating. A car rated at 6 L/100km will likely average 6.6–7.5 L/100km in mixed real-world conditions. Cold weather, city driving, roof boxes, and aggressive acceleration all push the number up.
How do I convert L/100km to US mpg in my head?
Divide 235 by the L/100km value. So 8 L/100km is roughly 235 ÷ 8 ≈ 29 mpg. For UK mpg, divide 282 instead. This mental shortcut is accurate enough for casual comparisons when shopping for cars across markets.
Why did Europe pick 100 km as the reference distance?
One hundred kilometers is a psychologically round number that keeps consumption figures in a convenient 3–20 range for most passenger cars. Using L/km would give tiny decimals (0.07), and L/1000km would give unwieldy large ones (70). The 100 km base hits the sweet spot for human readability.
What L/100km does a diesel car achieve compared to petrol?
Diesel engines are typically 15–25% more fuel-efficient than equivalent petrol engines. A petrol car rated at 7 L/100km might have a diesel counterpart at 5.5–6 L/100km. However, diesel fuel contains about 13% more energy per liter, so the CO₂ gap is smaller than the L/100km numbers suggest.
Gallons per 100 miles (UK) – Frequently Asked Questions
Why would anyone use imperial gallons per 100 miles?
Fleet managers and logistics companies in the UK sometimes prefer this consumption-based metric because it scales linearly with cost. If fuel costs £5.50 per imperial gallon, a vehicle using 3 gal/100mi costs exactly £16.50 per 100 miles — much easier to budget than working backwards from mpg.
How does UK gal/100mi compare to US gal/100mi for the same car?
UK gal/100mi values are about 17% lower than US gal/100mi because the imperial gallon is larger. A car consuming 4 US gal/100mi uses only about 3.33 UK gal/100mi. Same fuel burned, but fewer of the bigger gallons needed to measure it.
How do UK fleet operators use gal/100mi to set carbon budgets per vehicle?
Burning one imperial gallon of diesel produces about 10.2 kg of CO₂. Multiplying gal/100mi by that emission factor gives a direct kg-CO₂-per-100-miles figure for each vehicle. Fleet managers set thresholds — say 25 kg CO₂/100mi — and flag any vehicle exceeding it for maintenance or driver retraining. The linear relationship makes gal/100mi far better than mpg for carbon accounting, where small absolute savings matter.
What is a good UK gal/100mi for a family car?
A modern family hatchback should achieve around 1.8–2.3 UK gal/100mi (43–56 UK mpg). Anything under 2 gal/100mi is considered very efficient. SUVs typically sit at 2.5–3.5 gal/100mi, and performance cars can exceed 4 gal/100mi.
Is this unit used on any official UK documentation?
Not on consumer-facing documents. UK vehicle registration (V5C) and type-approval certificates show L/100km and CO₂ g/km. Gal/100mi (imperial) lives mainly in fleet management software, academic transport research, and engineering reports where linear consumption comparisons matter more than the traditional mpg framing.