Petrol vs Diesel vs Electric: Running Cost Comparison

Understanding UK Fuel Type Running Costs

The cost of running a car varies enormously depending on its fuel type. At 2025 rates, a petrol car costs roughly 16p per mile in fuel alone, while a fully electric vehicle costs just 5p per mile when charged at home on a standard tariff. That difference may sound small, but over 10,000 miles a year it adds up to more than£1,100 in annual savings -- enough to cover a year of car insurance for many drivers.

Diesel has traditionally been the choice for high-mileage drivers, and the numbers still support that logic. Despite costing more per litre at the pump, diesel engines squeeze more miles from each litre, bringing the per-mile cost down to around 14p. For drivers covering 20,000 miles or more annually, diesel saves roughly £400 over petrol each year. However, diesel's advantage is narrowing as pump prices converge and clean air zones penalise older diesel vehicles with daily charges of £12.50 or more.

Hybrid vehicles occupy a useful middle ground. With a per-mile cost of around 10.4p, they offer meaningful savings over both petrol and diesel without the range anxiety or charging infrastructure requirements of pure electric cars. Plug-in hybrids can push this figure even lower for drivers who regularly charge at home and make mostly short journeys, though real-world economy depends heavily on how often the battery is topped up.

When Does an EV Make Financial Sense?

The total cost of ownership (TCO) calculation goes well beyond fuel. Electric vehicles benefit from zero road tax (VED), lower servicing costs due to fewer moving parts, and reduced brake wear thanks to regenerative braking. Against this, EVs carry a purchase price premium of around £8,000 to £12,000 over an equivalent petrol car. Using a conservative £8,000 premium and fuel savings of 11p per mile, a driver covering 10,000 miles annually would break even in roughly 7.3 years. At 20,000 miles a year, that drops to under 4 years.

The financial case for EVs strengthens further when you factor in off-peak electricity tariffs (some as low as 7p per kWh), salary sacrifice schemes that eliminate benefit-in-kind tax, and the growing network of free workplace chargers. For company car drivers, the 2% BIK rate on EVs versus 20-37% for petrol cars can save thousands per year in tax alone.

The Decline of Diesel

Diesel's share of new car sales has fallen dramatically, from a peak of nearly 50% in 2012 to below 5% in 2025. The “Dieselgate” emissions scandal, tightening Euro emission standards, and the expansion of Clean Air Zones across UK cities have all contributed to a rapid shift away from diesel. Resale values for diesel cars have softened accordingly, adding depreciation as a hidden cost for current owners. While diesel remains a rational choice for a shrinking pool of use cases -- long-distance motorway driving, towing, and commercial vehicles -- the writing is on the wall for diesel as a mainstream passenger car fuel.

For most UK drivers doing the national average of around 7,400 miles per year, the decision increasingly favours electrification. If an EV fits your budget and lifestyle, the running cost savings are substantial. If not, a hybrid offers a pragmatic stepping stone with noticeably lower fuel bills and emissions than either petrol or diesel.