L/100km vs MPG
They measure the same thing inversely — litres-per-distance vs distance-per-gallon. The conversions:
MPG(US) = 235.215 ÷ (L/100km) · MPG(UK) = 282.481 ÷ (L/100km)
Note the UK gallon is ~20% bigger than the US gallon, so UK MPG numbers always look higher for the same car. Choose a currency above and enter the local pump price. The selector labels the calculation; it does not apply an exchange rate.
FAQ
Why does economy matter for a tuned car?
More power usually means more fuel under load. This makes the trade-off concrete — see the yearly cost change when your consumption goes up by a litre or two.
US or UK gallons?
The calculator shows both. Pick the one that matches where you fill up.