Petrol vs diesel fuel calculator
Our fuel-cost calculator below lets you quickly work out and compare the annual fuel costs between two cars (petrol and diesel, or otherwise).
We also report our own mpg figures for every car we test.
Our rigorous car tests are based on real-world driving. We simulate city and out-of-town roads, plus motorways - something the official tests don't do. As well as providing you with an , we report each figure separately. That way you can actually see what the numbers mean for your wallet based on your typical type of driving.
Petrol vs diesel fuel-cost calculator: is the diesel premium worth it?
- Click the Add another car for comparison option.
- Add the fuel-economy figures for two cars.
- Add your annual mileage (most Which? members drive about 9,000 miles each year).
Petrol car annual running costs
Below, we’ve crunched the numbers to calculate annual fuel costs for three of the most popular models across the small, medium and SUV car classes. Given the downturn in demand for diesel cars, we’ve focused solely on the petrol models we’ve tested.
Each of our contains independent, lab-tested fuel economy data for every engine version we’ve tested. You can easily compare fuel costs as we tell you how much each engine will set you back in monthly and annual fuel bills.