How to Use This Calculator

Getting accurate savings estimates is straightforward. Start by entering your annual mileage – you can find this by checking your MOT history or tracking your odometer over a few months. The average UK driver covers about 7,400 miles yearly, but your actual figure matters most.

Next, check your current fuel prices at your local petrol station. Prices vary by region and retailer, so use what you actually pay rather than national averages. For electricity rates, look at your current energy bill or explore dedicated EV tariffs from providers like Octopus Energy, British Gas, or EDF, which offer off-peak rates as low as 7-9p per kWh.

Your vehicle’s MPG can be found in your car’s trip computer or by dividing miles travelled by fuel consumed. For EVs, efficiency typically ranges from 3.0 to 4.5 miles per kWh depending on the model – a Tesla Model 3 achieves around 4.1, while larger SUVs like the Audi e-tron sit closer to 2.8.

Public Charging Considerations

If you live in a flat or lack home charging, you’ll rely more on public infrastructure. Adjust the public charging percentage accordingly. Rapid chargers at motorway services cost significantly more (55-89p/kWh) than home charging, but destinations like supermarkets often offer cheaper rates or even free charging.

What Drives Your Savings

The massive cost difference between electric and traditional vehicles comes down to three key factors that work together to slash your running expenses.

Energy Costs

Electricity is substantially cheaper than petrol or diesel per mile. At 9p/kWh on an off-peak tariff, an EV achieving 3.5 miles/kWh costs just 2.6p per mile to run. Compare that to a petrol car averaging 45 MPG at £1.37/litre, which costs 13.8p per mile – over five times more expensive.

This gap widens if you can charge at work for free or use public chargers at supermarkets during your shopping. Even expensive rapid chargers at 65p/kWh only cost 18.6p per mile – still competitive with petrol.

Maintenance Savings

Electric motors have roughly 20 moving parts compared to over 2,000 in a combustion engine. There’s no oil to change, no spark plugs to replace, no timing belts to worry about. Brake wear is minimal thanks to regenerative braking. Most EV owners report annual servicing costs of £150-£250 versus £300-£550 for petrol and diesel vehicles.

Tax Benefits

From April 2025, new EVs pay just £10 first-year Vehicle Excise Duty (VED), then £195 annually thereafter. If your EV costs over £40,000 when new, you’ll pay an additional £425 yearly luxury supplement for years 2-6, but this still beats the £605 annual cost for expensive petrol or diesel cars.

Company car drivers benefit enormously from Benefit-in-Kind (BiK) rates of just 3-5% for EVs versus 25-37% for conventional vehicles. On a £40,000 EV, a 40% taxpayer pays around £480-£800 yearly BiK tax compared to £4,000+ for an equivalent petrol car.

Frequently Asked Questions

Maximising Your Savings

Smart Charging Strategies

Switching to a dedicated EV energy tariff is the single biggest saving you can make. Off-peak rates of 7-10p/kWh versus standard 26-27p/kWh can save you £400-£600 annually on a typical 10,000-mile driving pattern. Set your car or charger to automatically charge during off-peak hours.

Many workplaces now offer free or subsidised charging – even one or two charges weekly can cut your costs by 20-30%. Supermarkets like Tesco, Sainsbury’s, and Lidl often provide free 7kW chargers for customers. A weekly shop could net you 30-40 kWh of free electricity worth £8-12.

Choosing the Right EV

Efficiency varies dramatically between models. A Hyundai Ioniq 6 or Tesla Model 3 can achieve 4.5+ miles/kWh, while luxury SUVs like the Audi e-tron or Mercedes EQC manage closer to 2.5-3.0. That difference costs £300-£500 yearly on 10,000 miles. If efficiency matters more than size, smaller EVs deliver bigger savings.

Driving Style Matters

Gentle acceleration, using Eco mode, and maximising regenerative braking can improve efficiency by 15-20%. This isn’t just about saving money – smoother driving also reduces tyre wear and extends battery life. Learn your car’s efficiency displays and experiment to find what works.

Cost Comparison by Vehicle Type

Figures based on December 2025 UK averages: petrol £1.37/L, diesel £1.46/L, electricity 9p/kWh off-peak or 65p/kWh public rapid. Assumes 45 MPG petrol, 52 MPG diesel, 3.5 mi/kWh electric.

Common Calculation Mistakes

Using Standard Electricity Rates

Many people calculate EV costs using their current 26-27p/kWh rate and conclude EVs are barely cheaper than petrol. This completely misses the point of EV-specific tariffs. Always use off-peak rates (7-10p/kWh) for accurate home charging costs.

Forgetting Standing Charges

Some EV tariffs have higher daily standing charges to offset cheap off-peak rates. Calculate total household electricity costs, not just per-kWh rates. For low-mileage drivers doing under 5,000 miles yearly, standard tariffs might actually cost less overall.

Ignoring Efficiency Variations

Manufacturer claims show best-case efficiency. Real-world driving, especially motorway miles, heating or air conditioning use, and cold weather all reduce efficiency. Budget for 15-20% below official figures for realistic costs.

Overlooking Luxury Car Tax

EVs over £40,000 when new pay an extra £425 yearly for years 2-6 of ownership. This adds £2,125 to your total cost of ownership. It doesn’t apply to used EVs that were under £40,000 when new, even if you pay more than £40,000 for them secondhand.

Not Accounting for Depreciation Differences

While not captured in this calculator, EVs historically depreciated faster than petrol cars, though this gap is closing as the used market matures. Factor in total cost of ownership including purchase price and resale value for the complete picture.