Gallons per 100 miles (US) to Liters per 100 km
gal/100mi (US)
L/100km
Conversion History
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Quick Reference Table (Gallons per 100 miles (US) to Liters per 100 km)
| Gallons per 100 miles (US) (gal/100mi (US)) | Liters per 100 km (L/100km) |
|---|---|
| 1.5 | 2,834.2913833200000000141714569166 |
| 2 | 2,125.71853749 |
| 2.5 | 1,700.574829992 |
| 3 | 1,417.1456916599999999858285430834 |
| 4 | 1,062.859268745 |
| 5 | 850.287414996 |
| 6.7 | 634.5428470119402985093663151082 |
About Gallons per 100 miles (US) (gal/100mi (US))
Gallons per 100 miles (US) — abbreviated gal/100mi — is a consumption metric, the American analogue to the European L/100km standard. Lower is better. It is the mathematical inverse of US mpg multiplied by 100. The US EPA introduced the GPM metric alongside mpg to help consumers make better fuel economy comparisons: because mpg is non-linear, the true fuel saving from improving a 15 mpg truck to 20 mpg (1.67 gal/100mi saved) is far larger than improving a 40 mpg car to 50 mpg (0.5 gal/100mi saved). GPM makes this intuitively clear by expressing absolute consumption rather than efficiency.
A 25 mpg family sedan consumes 4 gal/100mi. A 50 mpg hybrid uses only 2 gal/100mi — saving as much fuel per mile as the difference from 10 to 50 mpg on a low-efficiency vehicle.
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.
Gallons per 100 miles (US) – Frequently Asked Questions
Why did the EPA start showing gallons per 100 miles on window stickers?
Research by Duke University professors showed that mpg systematically misleads consumers about fuel savings. The EPA added gal/100mi to Monroney stickers starting in 2013 to give buyers a linear, comparable number. A 1 gal/100mi difference always represents the same fuel saving regardless of starting point.
How does gal/100mi help compare plug-in hybrids that switch between fuel and electricity?
Plug-in hybrids complicate mpg because they drive some miles on electricity and some on petrol. Gal/100mi lets you weight the two modes transparently: if a PHEV uses 0 gallons for its first 40 electric miles and 2.5 gal/100mi after that, fleet managers can model exact fuel costs for any commute length. The EPA's MPGe tries to do something similar for consumers, but gal/100mi is more intuitive for mixed-mode budgeting.
What gal/100mi does the average American car use?
The average new car in the US uses about 3–4 gal/100mi (25–33 mpg). Full-size trucks sit around 5–7 gal/100mi, while hybrids achieve 1.5–2.5 gal/100mi. Electric vehicles show 0 gal/100mi but have a separate kWh/100mi rating.
Why do long-haul trucking companies obsess over fractions of a gal/100mi?
A Class 8 semi averages about 6.5 gal/100mi and covers 100,000+ miles per year — roughly 6,500 gallons annually. Shaving just 0.3 gal/100mi through aerodynamic fairings, low-rolling-resistance tires, or driver coaching saves ~300 gallons per truck per year. Across a 5,000-truck fleet, that is 1.5 million gallons saved — worth over $5 million at US diesel prices. At that scale, every tenth of a gal/100mi is a budget line item.
Why do Europeans never use gal/100mi even though they use L/100km?
Europeans adopted L/100km as their native metric from the start, so there was never a need for an alternative. Gal/100mi was invented specifically to fix the mpg illusion problem in the US. Europeans already had the "right" unit — they just used metric volumes and distances.
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.