Electric Car Savings Calculator

Switching from petrol or diesel to an electric vehicle can produce dramatic running-cost savings — but the actual size depends heavily on where you charge. Home charging on a smart EV tariff (Octopus Go, Intelligent Octopus, EDF GoElectric, OVO Charge Anytime) runs at 7-8p/kWh during off-peak windows in 2025/26, against domestic flat rate of about 27p/kWh. A typical efficient EV consumes 3.5-4.5 miles per kWh, so off-peak home charging costs roughly 1.5-2.3p per mile. Compare that to petrol at £1.40/litre and 40 MPG real-world: 4.546 litres × £1.40 ÷ 40 = 15.9p per mile. Diesel at £1.45/litre and 50 MPG works out at about 13.2p per mile. The off-peak EV cost is roughly 80-90% lower than petrol per mile. Public rapid charging is a different story. Rapid chargers (50 kW+) typically cost 70-85p/kWh in 2025, with ultra-rapid (150 kW+) sometimes over 90p/kWh — roughly 20-23p per mile, more expensive than petrol or diesel per mile and dramatically more expensive than home charging. A driver who only uses public rapids would actually pay more per mile than running a petrol car. The realistic savings calculation depends on the home/public split: this calculator asks for that ratio and applies the blended rate. Beyond fuel, EVs have other 2025/26 cost differentials. Company car Benefit-in-Kind (BIK) is 3% in 2025/26 for fully electric vehicles, rising by 1 percentage point per year (4% in 2026/27, 5% in 2027/28), versus 25-37% for petrol/diesel — a huge salary-sacrifice advantage. VED (road tax) for EVs registered from April 2025 is £10 first year then £195 standard from year 2 (same as petrol/diesel), plus the £425/year Expensive Car Supplement for any EV with list price over £40,000 — which catches most new EVs from years 2 to 6. EV insurance has typically been 15-25% higher than equivalent ICE cars due to repair costs, though gap narrowing in 2024-25 as the insurance market normalises. This calculator combines fuel/electricity cost, VED, insurance differential and BIK tax saving (where relevant) to produce a complete 5-year ownership comparison. It does not model home charger installation (£800-£1,500 with OZEV grant if you own a flat with eligible parking), depreciation differences, battery replacement risk (very low in practice on modern EVs with 8-year/100,000 mile warranties), or workplace charging benefits. For pure fuel cost use the Fuel Cost Calculator; for total ownership use the Car Running Cost Calculator.