Is diesel still worth it in the UK?

Diesel makes financial sense only for high-mileage drivers, typically above 12,000-15,000 miles per year. The higher purchase price and fuel cost per litre must be offset by better fuel economy. For low-mileage drivers, petrol is almost always cheaper overall.

Why are diesel cars more expensive to buy?

Diesel engines use higher compression ratios and require more robust components. They also have complex emissions equipment including diesel particulate filters (DPFs) and often AdBlue systems. This adds £1,000-£3,000 to the purchase price versus the petrol equivalent.

What about diesel depreciation?

Diesel cars have seen stronger depreciation recently due to clean air zones, potential city bans, and the shift towards electrification. This should be factored into the overall cost comparison, especially for newer cars.

How do I find the MPG for each fuel type?

Check the manufacturer specifications for the specific petrol and diesel models you are comparing. For real-world figures, sites like Fuelly and HonestJohn provide owner-reported averages that are more realistic than official WLTP figures.

Is diesel being phased out in the UK?

New diesel car sales will be banned from 2035 (along with petrol). Existing diesel cars will still be road legal. However, Clean Air Zones and ULEZ-style charges are making diesel less attractive in cities. For high-mileage drivers, diesel remains cost-effective until EV ranges improve further.

CarCalcs

Petrol vs Diesel Calculator

Compare the total running costs of petrol and diesel versions of the same car.

Annual Mileage

Ownership Period

Petrol

Petrol MPG (UK)

Petrol Price

Petrol Car Purchase Price

Diesel

Diesel MPG (UK)

Diesel Price

Diesel Car Purchase Price

How We Calculate This

This calculator compares the total cost of ownership between petrol and diesel versions, factoring in purchase price and fuel costs over your ownership period.

The Calculation

Annual fuel cost = (Annual miles / MPG) x 4.54609 x Fuel price per litre
Total cost = Purchase price + (Annual fuel cost x Years)
Break-even mileage = Price premium / Fuel saving per mile

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Actual figures may vary based on driving conditions, vehicle specifications, and other factors.