Electric Car vs Petrol Running Cost Calculator (UK)

EV vs Petrol Running Cost Guide (UK)

What should I know about Fuel Cost Reality?

Cost per mile varies massively by charging mix. Home-charged EV on cheap overnight tariff (Octopus Intelligent Go 7p/kWh): ~2p/mile in a typical EV (3.5 mi/kWh). Home-charged on standard tariff (28p/kWh): ~8p/mile. Public rapid charging (60-80p/kWh): ~20-25p/mile — often MORE expensive than petrol per mile. Modern petrol/diesel (45 MPG, £1.45/litre): ~14p/mile. Modern diesel (55 MPG, £1.50/litre): ~12p/mile. The picture: home charging + EV is far cheaper. Public-only charging EVs cost similar to, or sometimes more than, an efficient petrol car per mile, which is why home charging access is the single biggest factor in whether an EV actually saves money.

What should I know about The Charging Mix Question?

Charging where matters enormously. Home charging requires: driveway/garage with off-street parking. 7kW home charger installation (£800-1,400 plus £350 OZEV grant if eligible). Smart tariff: Octopus Intelligent Go (7p off-peak overnight), Octopus Go (8p off-peak), British Gas Electric Driver, EDF Go Electric. Public charging access via: Tesla Supercharger (typically 30-50p/kWh for Tesla owners, varying public access pricing). InstaVolt rapid (60p+/kWh). Ionity (60-75p depending on contract). BP Pulse and Shell Recharge sit at similar rapid-charging price points, generally in the 55-70p/kWh range depending on location and membership tier.

What should I know about Beyond Fuel: Total Cost of Ownership?

Vehicle Excise Duty (VED / road tax): EVs ZERO until April 2025. From April 2025 EVs pay VED — £190/year for cars over £40,000 valuation. Expensive Car Supplement: £410 supplemental annual tax for cars over £40,000 list price (years 2-6). Applies to many EVs. Insurance: EVs typically 20-30% more expensive than equivalent petrol. Repair costs higher, fewer specialist mechanics. Maintenance: EVs cheaper to service. No oil, no spark plugs, no exhaust, no clutch (in single-speed EVs), regenerative braking that reduces brake pad and disc wear significantly compared to a petrol or diesel car.

When EV Makes Financial Sense?

Best case for EV economics: own driveway/garage for home charging. High annual mileage (12,000+ miles). Smart tariff access (Octopus etc.). Salary sacrifice scheme available (BIK tax 2% for EVs 2026/27 saves huge sums for higher-rate taxpayers). Worst case for EV economics: street parking without charging access. Low annual mileage (under 5,000 miles — fuel savings don't outweigh higher purchase price). Long-distance driving heavy on public rapid charging. Crossover: the typical break-even point for a new EV against an equivalent petrol car is usually reached somewhere between 3 and 6 years of ownership, depending on annual mileage and charging access.

What's the key thing to understand about Comparing Cost Per Mile Fairly?

A fair running cost comparison between an electric vehicle and a petrol or diesel equivalent needs to look beyond the per-litre or per-kWh price alone, since the two technologies convert energy to distance very differently. A typical electric vehicle might use somewhere in the range of 0.2–0.3 kWh per mile depending on the model, driving style, and conditions, while a typical petrol car might use roughly 0.1–0.15 litres per mile — multiplying each by the relevant energy price per unit gives a genuine cost-per-mile figure that can then be directly compared. The actual cost gap between the two depends heavily on where and when electricity is bought: home charging on a standard domestic tariff is usually meaningfully cheaper per mile than petrol, home charging on a dedicated off-peak EV tariff (charging overnight when rates are lowest) is typically cheaper still and often represents the biggest cost advantage EVs have over petrol cars, while relying heavily on public rapid or ultra-rapid charging networks — which charge a premium for speed and convenience — can sometimes cost close to, or even exceed, the per-mile cost of driving a petrol car, eroding much of the running-cost advantage for EV owners without reliable access to home charging. This is why access to off-street parking and home charging is one of the biggest single factors in whether an EV genuinely delivers lower running costs for a specific driver.

What should I know about Total Cost of Ownership Beyond Fuel/Energy?

Running cost comparisons that stop at fuel or electricity cost miss other significant differences between EV and petrol ownership. Servicing and maintenance costs are generally lower for EVs, since they have far fewer moving parts than an internal combustion engine — no oil changes, no exhaust system, no spark plugs or timing belt, and brake wear is often reduced too, because regenerative braking (which also feeds energy back into the battery) does much of the slowing-down work in normal driving rather than the physical brakes alone. Depreciation has historically been a more significant and less predictable cost for EVs than for petrol cars, since rapidly improving battery technology and falling prices on new EVs have sometimes caused faster-than-expected depreciation on older EV models, though this pattern has been evolving as the EV market matures and should be checked against current used-market data rather than assumed to always apply. Insurance can be somewhat higher for EVs in some markets, partly reflecting higher repair costs for specialist battery and electronic components, though this gap has been narrowing as EVs become more common and repair networks develop. Taken together, a genuinely complete comparison needs to weigh purchase price, fuel/energy cost, servicing, insurance, and expected depreciation over a realistic ownership period — not fuel cost alone — since a vehicle that's cheaper to run day-to-day can still cost more overall if it depreciates faster or costs more to insure.

Worked Example: 12,000 Miles a Year, Head to Head

Compare a mid-size EV doing roughly 3.5 miles per kWh against an equivalent petrol car averaging 45mpg, both covering 12,000 miles a year. EV charged mostly at home off-peak (around 8p/kWh), with occasional public charging: 12,000 / 3.5 = 3,430 kWh needed At a blended rate of roughly 12p/kWh (mostly cheap home charging, some pricier public top-ups): 3,430 x £0.12 = approximately £412/year Petrol car at 45mpg and a typical pump price of around £1.50-£1.55/litre: 12,000 miles / 45mpg = 267 UK gallons = 1,212 litres 1,212 x £1.50 = approximately £1,820/year That is a fuel saving of roughly £1,400 a year in the EV's favour — but fuel is only one line in the total cost comparison. Servicing is typically cheaper for an EV (no oil changes, fewer moving parts, less brake wear thanks to regenerative braking), while insurance can run higher for some EV models due to battery repair costs, and depreciation is the wildcard: some EVs have depreciated faster than equivalent petrol cars as battery technology and government incentives shift, while others now hold value comparably. The fuel saving alone is rarely enough to judge total cost of ownership — it needs to be weighed against the purchase price gap, as the running-cost comparison on this page sets out.

Reference: What Changes the Comparison Most

The single biggest lever most households control is charging location: a driver who can charge almost entirely at home overnight gets a fundamentally different cost picture from one who depends on public rapid chargers, which often cost 3-5 times the home off-peak rate and can occasionally approach the cost per mile of petrol.

What should I know about Insurance Cost Differences?

EVs have historically sat in higher insurance groups than equivalent petrol models, mainly because battery packs and specialist EV parts are expensive to repair or replace after even minor collision damage, and fewer garages are certified to work on high-voltage systems. This gap has been narrowing as EVs become mainstream and more bodyshops gain EV certification, but it's still common to see an EV quoted £100-£300 a year more to insure than a similarly priced petrol equivalent. This cost sits outside the fuel-versus-electricity comparison most people focus on, but it's real enough to matter in a full running-cost comparison, particularly for newer drivers or higher-value EVs where the insurance group gap is widest.