Electric Car vs Petrol Calculator

The EV question in 2026

Electric cars have moved from early-adopter territory to mainstream consideration. New EV prices still carry a premium over equivalent petrol cars — typically 3,000 to 8,000 depending on segment — but running costs are dramatically lower. The question for most buyers is not whether EVs are cheaper over the lifetime of ownership, but how many years of ownership it takes to recover the upfront premium.

This calculator compares the two routes using your annual mileage, the price gap, and current fuel and electricity prices that you enter yourself. Prices change — rates are user inputs rather than hardcoded numbers — so the math stays accurate whatever the energy market is doing.

Where EVs save money

Fuel cost per mile. A typical family petrol car at 45 mpg costs around 14 to 16 pence per mile at 1.45/litre. A typical EV driven with mostly home charging at 8 p/kWh (off-peak Octopus Go, Intelligent Octopus) costs around 2 to 3 pence per mile. Even at 28 p/kWh peak rates the per-mile cost is around 7 to 8 pence. Over 10,000 annual miles that is 600 to 1,400 a year in fuel savings.

Servicing and maintenance. EVs have fewer moving parts — no oil, no spark plugs, no timing belt, no clutch, no gearbox oil — so routine servicing runs roughly 30 to 50 per cent cheaper. Brakes last longer because regenerative braking does much of the slowing. Typical annual savings run 200 to 400 for an EV versus petrol.

Vehicle Excise Duty and company car tax. EVs currently pay 0 or minimal VED (rules are changing — check current rates). For company car drivers, the tax rate on EVs is 3 per cent versus 25 to 37 per cent for equivalent petrol cars — that indicates differences of 2,000 to 6,000 a year in tax on a 50,000 company car.

Where petrol still wins

Purchase price. A Volkswagen Golf starts around 26,000 petrol versus 36,000 for an ID.3 electric equivalent. That 10,000 gap is the headwind EVs must overcome through fuel and maintenance savings.

Depreciation. EV residual values softened as second-hand EV supply grew and battery concerns persisted. Some EVs lost 40 per cent in two years, worse than petrol equivalents. Residual values are stabilising but remain model-dependent.

Long-distance driving. If your mileage is dominated by motorway trips and you cannot charge at home, EV costs rise substantially. Rapid-charger rates of 60 to 85 p/kWh mean the per-mile cost can match or exceed petrol. EVs tend to be cost-effective for people who charge at home overnight and drive mostly local or regional.

The break-even math

Take the purchase price gap (EV price minus petrol price) and divide by annual fuel-plus-maintenance savings. The result is years to break even.

Worked example: 10,000 EV premium, 12,000 miles a year, 45 mpg petrol at 1.45/litre, EV at 3 p/mile mostly home charged. Petrol fuel cost: ~1,760 a year. EV fuel cost: ~360 a year. Fuel saving alone: 1,400. Add 300 maintenance savings: 1,700 a year. Break-even: roughly 5.9 years.

At 20,000 miles a year the same math gives break-even in 3.5 years. At 6,000 miles a year it stretches past 10 years — at which point the car is probably being replaced before it has paid back.

The charging question dominates everything

Home charging changes the economics by a factor of 5 to 10. A household with a driveway, a 7 kW charger, and an EV tariff pays around 2-3 p/mile. A household charging exclusively at public rapid chargers pays 15-20 p/mile. The difference across 10,000 miles is 1,200 to 1,700 a year — more than the annual cost of a small petrol car.

Before committing to an EV, confirm: can you install a home charger, what electricity tariff can you get, and is there reasonable public charging near places you regularly visit? If home charging is not possible, run the numbers again at public-charger rates to see the impact on costs.

Non-financial factors

Beyond the units: EVs are quieter, torquier, have fewer service visits, and produce no tailpipe emissions. Some cities charge daily fees on older petrol/diesel cars that EVs avoid entirely. EVs also allow Vehicle-to-Load and Vehicle-to-Grid applications that are maturing. Petrol cars have a denser refuelling network, faster refuelling, and — for now — wider second-hand choice.

What the calculator does not include

The model handles fuel cost per mile. It does not include insurance differences (EVs typically cost more to insure), VED, charger installation costs (800-1,200 upfront, partially covered by grants), depreciation, or regional subsidies. For a complete lifetime-cost picture combine this output with separate insurance quotes and an honest depreciation estimate for the specific models you are comparing.