Cars & Motoring2 min check

Petrol vs Diesel vs EV Calculator

Compare annual fuel/energy costs for petrol, diesel and EV cars at your real-world mileage and prices.

Short answer

Petrol pence/mile = (100 ÷ MPG) × (price per litre × 4.546). EV pence/mile = (100 ÷ mi/kWh) × pence/kWh ÷ 100. At typical UK rates: petrol ≈ 14–18p/mile; EV at home off-peak ≈ 2–3p/mile; EV on rapid ≈ 16–20p/mile.

Step 1 of 20%

Calculation method, coverage and version

Inputs used: Annual mileage, Petrol (£/litre), Petrol MPG, Diesel (£/litre), Diesel MPG, EV blended rate (p/kWh), EV mi/kWh.
Calculation approach: The calculator applies the rules and assumptions described in “How it works” to the values you enter. Rounding can cause small differences from an official or provider calculation.
Coverage: Cars & Motoring. UK nations, tax treatment, local rules and provider criteria can differ; check the official sources shown below before acting.
Content version: No page-specific review date is currently published. Treat the result as indicative and verify current rules independently.

Not included unless explicitly requested: personal circumstances not entered, provider discretion, future rule changes, professional fees and case-specific exceptions. Read the full calculator methodology.

How it works

We convert MPG to L/100mi using the imperial gallon (4.546L), multiply by fuel price, and compare against EV efficiency × electricity rate. Then we project the annual saving over your typical mileage.

Worked example

10,000 miles/year. Petrol 50 MPG at £1.45/L = £1,318. EV 3.8 mi/kWh at 7p home = £184. Annual saving £1,134 — pays back a £6,000 EV price premium in ~5 years on fuel alone.

Who should use this

•Drivers considering switching to EV
•Hybrid vs full-EV comparison
•Fleet decision-makers

Common mistakes

×Comparing showroom MPG to real-world EV efficiency
×Ignoring that EVs save service costs (no oil changes, fewer brake wear)
×Forgetting depreciation differs sharply between fuel types

Frequently asked questions

Are EVs always cheaper to run?▾

Almost always on home charging; close to break-even on rapid-only public charging.

Do hybrids save money?▾

Self-charging hybrids save 10–15% on fuel. PHEVs only if you actually plug in daily.

What about diesel?▾

Diesels are similar to petrol on long runs but penalised by ULEZ/clean air zones in many cities.

Related calculators

EV Charging →Running Costs →Depreciation →ULEZ Checker →