Fuel efficiency is measured in completely different ways across the world, making it confusing when comparing vehicles internationally. The US uses miles per gallon (MPG), most of the world uses liters per 100 km (L/100km), and the UK sometimes uses miles per liter (MPL). These are not directly proportional conversions because they're calculated differently.
The Conversions
MPG (US) to L/100km:
L/100km = 235.214 / MPG
MPG = 235.214 / L/100km
MPG (UK) to L/100km:
L/100km = 282.481 / MPG (UK)
MPG (UK) = 282.481 / L/100km
MPG (US) to MPG (UK):
MPG (UK) = MPG (US) × 1.20095
MPG (US) = MPG (UK) / 1.20095
Worked Example
A car gets 30 MPG (US). What is this in L/100km?
L/100km = 235.214 / 30 = 7.84 L/100km
This car consumes 7.84 liters per 100 kilometers. Conversely, if a European car uses 5 L/100km:
MPG (US) = 235.214 / 5 = 47 MPG
Why the Difference?
The conversions aren't simple reciprocals because:
- US gallon ≈ 3.785 liters (smaller than imperial gallon)
- US mile ≈ 1.609 km
- L/100km is consumption per distance, while MPG is distance per volume
- The reference distances are different (100 km vs miles)
Common Fuel Efficiency Ranges
| Vehicle Type | MPG (US) | L/100km |
|---|---|---|
| Efficient sedan | 35–45 | 6–7 |
| Average sedan | 25–30 | 8–9 |
| SUV | 20–25 | 9–12 |
| Sports car | 15–20 | 12–16 |
| Hybrid | 45–60 | 4–5 |
| Electric | N/A | 15–20 kWh/100km |
For electric vehicles, energy is measured in kWh/100km instead of fuel volume.
Practical Comparison
A US driver seeing 30 MPG should understand this is decent (European average is about 7–8 L/100km). A European driver seeing 9 L/100km is average. Same efficiency, different numbers.
Tips
When comparing vehicles across regions, always convert to the same unit first. Also remember that real-world fuel efficiency is typically 10–20% worse than official EPA estimates due to driving conditions, speed, and vehicle load.
Use our Fuel Efficiency Converter to convert between MPG, L/100km, and other efficiency units instantly.