Gas vs Diesel Calculator
Petrol or diesel? Compare the annual fuel bill for both using your distance, each fuel price and each engine consumption to see which one is cheaper to run.
How it works
Annual fuel cost = distance ÷ 100 × consumption × fuel price. Diesel usually needs fewer litres (better efficiency) but the per-litre price and the higher purchase price of diesel cars must be weighed against servicing and possible city access restrictions.
Frequently asked questions
Is diesel always cheaper to run?
Usually on fuel alone for high annual mileage, because diesel engines burn fewer litres per 100 km. But diesel cars cost more to buy, need more expensive servicing (DPF, injectors), and face restrictions in some cities.
At what mileage does diesel pay back?
As a rule of thumb diesel often breaks even above 15,000–20,000 km per year. Below that, the higher purchase price usually outweighs the fuel savings. Re-run this calculator with your real figures.