Fuel cost formulas
Metric: cost = km × (L/100 km) ÷ 100 × price per liter
US: cost = miles ÷ mpg × price per gallon
Example
A 350 km drive in a car that uses 6.5 L/100 km needs 350 × 6.5 ÷ 100 = 22.75 liters. At 1.85 per liter, that costs about 42.09. A round trip doubles it to 84.18.
Ways to save fuel
- Slow down a little: most cars use noticeably more fuel above about 90 km/h (55 mph).
- Keep tires properly inflated: under-inflated tires increase rolling resistance.
- Remove roof boxes and racks when you don't need them.
- Drive smoothly: gentle acceleration and anticipating stops can save 10–20%.
