Petrol vs Diesel Calculator
Compare the real-world running costs of petrol and diesel vehicles. Enter your annual mileage, fuel economy, and current pump prices to see which fuel type saves you more.
Your Driving Profile
UK average is roughly 7,400 miles per year.
Vehicle type presets
Check current prices near you.
How much more the diesel version costs to buy. Set to 0 if comparing running costs only.
How It Works
The calculator estimates the annual litres of fuel each engine type would consume based on your mileage and MPG figures, then multiplies by the price per litre to produce a yearly cost. It also factors in the higher purchase price of a diesel model to show how long it would take to break even on fuel savings alone.
When Does Diesel Make Sense?
- High annual mileage — diesel engines are more efficient, so the savings grow with the miles you drive. Drivers doing 15,000+ miles per year tend to benefit most.
- Motorway-heavy driving — diesel efficiency shines on long, steady runs. Short urban trips often erode the advantage.
- Long ownership — if you keep cars for 5+ years, there is more time to recoup the diesel premium.
- Towing or heavy loads — diesel torque makes it the preferred choice for caravans and trailers.
When Petrol Is the Better Choice
- Low annual mileage — under 8,000 miles a year, the diesel premium is hard to recover.
- Mostly city driving — petrol engines warm up faster and cope better with stop-start traffic.
- Clean Air Zones — some older diesels face ULEZ and CAZ charges that petrol equivalents avoid.
- Lower purchase price — petrol models are typically cheaper to buy and insure.