Imperial Miles Per Gallon to Liters Per 100 Km
40 imperial miles per gallon equals 7.062 liters per 100 km. The two run in opposite directions, so a higher figure on one side is a lower figure on the other.
L/100km = 282.4809363 ÷ MPG (UK)
Fuel Economy Conversion
Vehicle Fuel Economy Examples
Fuel Economy Reference Guide
Understanding Fuel Economy Units
MPG (Miles per Gallon): Distance traveled per unit of fuel
L/100km: Fuel consumed per 100 kilometers (lower is better)
km/L: Distance per liter (higher is better)
US vs UK Gallons: US gallon = 3.785L, UK gallon = 4.546L
Inverse Relationship: Higher MPG = Lower L/100km
Global Standards: Most countries use L/100km
Fuel Efficiency Categories
Excellent: 40+ MPG (5.9 L/100km or less)
Good: 30-39 MPG (6.0-7.8 L/100km)
Average: 20-29 MPG (8.1-11.8 L/100km)
Below Average: 15-19 MPG (12.4-15.7 L/100km)
Poor: Under 15 MPG (over 15.7 L/100km)
Hybrid/Electric: 50+ MPG equivalent
Conversion Quick Reference
• 30 MPG (US) ≈ 7.84 L/100km ≈ 12.75 km/L
• 40 MPG (US) ≈ 5.88 L/100km ≈ 17.01 km/L
• 50 MPG (US) ≈ 4.70 L/100km ≈ 21.26 km/L
• 6 L/100km ≈ 39.2 MPG (US) ≈ 16.67 km/L
Imperial Miles Per Gallon to Liters Per 100 Km Conversion Table
| MPG (UK) | L/100km |
|---|---|
| 15 | 18.8321 |
| 20 | 14.124 |
| 25 | 11.2992 |
| 30 | 9.416 |
| 35 | 8.0709 |
| 40 | 7.062 |
| 45 | 6.2774 |
| 50 | 5.6496 |
| 55 | 5.136 |
| 60 | 4.708 |
| 70 | 4.0354 |
| 80 | 3.531 |
| 90 | 3.1387 |
| 100 | 2.8248 |
About This Conversion
Imperial miles per gallon to liters per 100 km converts UK fuel-economy figures, which use the 4.54609-liter imperial gallon, into the metric standard. Divide 282.4809363 by the MPG figure.
The gallon difference is why a UK figure always looks better than a US one for the same car. A car doing 48 UK MPG and one doing 40 US MPG are equally efficient, both around 5.9 L/100km. Comparing a UK road-test figure directly against a US EPA figure overstates the UK car by about 20 percent.
Frequently Asked Questions
What is 40 UK MPG in L/100km?
40 imperial MPG is 7.06 L/100km.
What is the formula?
Divide 282.4809363 by the imperial MPG figure. The constant is 100 × 4.54609 ÷ 1.609344.
How does UK MPG compare to US MPG?
An imperial MPG figure is about 1.201 times the US figure for the same car, because the imperial gallon is larger.
Which gallon do UK car reviews use?
The imperial gallon, 4.54609 liters.
Worth Knowing
US Gallon vs Imperial Gallon
A US gallon is 3.785411784 litres and an imperial (UK) gallon is 4.54609 litres, making the imperial gallon about 20.1 percent larger.