Miles driven over gallons burned
To measure it for real, fill the tank, zero the trip odometer, drive, then refill and divide the trip miles by the gallons it took to top off. That refill amount is exactly the fuel you burned. Higher MPG is better — the opposite of the L/100km scale used in most of the world, where lower is better.
What counts as good, by vehicle
| Vehicle | Typical MPG | L/100km |
|---|---|---|
| Large SUV / pickup | 15–22 | 11–16 |
| Midsize sedan | 28–34 | 7–8 |
| Compact car | 32–40 | 6–7 |
| Hybrid | 45–55 | 4–5 |
| US new-car average | ~27 | ~8.7 |
To convert, L/100km = 235 ÷ MPG. Real-world MPG often runs below the EPA sticker, especially for heavy vehicles and city driving, aggressive acceleration, or a cold engine.
Why +1 MPG matters far more on a thirsty car
Fuel used per mile is 1 ÷ MPG, so the scale is not linear. Adding 1 MPG to a 15-MPG truck saves several times more gas than adding 1 MPG to a 34-MPG sedan, even though both are "+1."
Same +1 MPG, but the low-MPG upgrade cuts fuel use more than twice as much. Swapping a gas-guzzler for something a little better beats fine-tuning an already efficient car.
Common questions
How do I calculate my car's MPG?
Fill the tank, reset the trip odometer, and drive normally. At the next fill-up, divide the miles you drove by the gallons it took to refill. If you went 350 miles on 12 gallons, that is 350 divided by 12, or 29.2 MPG.
What is a good MPG?
For a gas car, the low 30s is average, the high 30s and up is good, and 45-plus usually means a hybrid. Under 20 MPG is thirsty, typical of large SUVs and trucks. The US new-car average is around 27 to 28 MPG.
Is US MPG the same as UK MPG?
No. A UK gallon is about 20% larger, so the same car shows a higher number in UK MPG. Multiply US MPG by 1.2 to get UK MPG: 30 US MPG is about 36 UK MPG for the exact same fuel use.
