Vehicle Tools

What these tools are for

The calculators on this page all answer the same underlying question in different ways: what will this car actually cost you? The sticker price or monthly finance figure is only one part of the picture. Vehicle tax, fuel or electricity, and the steady loss of value as the car ages all add to the total, and they can vary enormously between two cars that look similarly priced on a forecourt. Each tool below handles one of those costs, so work through them in the order that suits your situation.

Checking tax before you commit

Vehicle tax is the first cost most buyers overlook, because it is not shown on the price tag and it changes depending on when the car was registered and what it emits. Cars registered on or after 1 April 2017 pay a CO2-based first-year rate, then a flat standard rate from the second year onwards. That standard rate is £200 for a single 12-month payment, or £210 if you pay by 12 monthly Direct Debits, and it applies to all fuels including electric.

Electric cars are no longer exempt. They stopped being exempt on 1 April 2025, so an EV now carries the same standard rate as a petrol or diesel car from its second year. A car tax calculator is the quickest way to see the first-year figure for a specific model, since the bands rise steeply as emissions increase and two cars with similar performance can sit in very different bands.

Two further points are worth knowing before you buy:

• A diesel that does not meet the RDE2 standard pays the first-year rate of the next band up. This applies to the first year only.
• The Expensive Car Supplement adds £440 a year for five years, starting from the second time the vehicle is taxed, if the list price was over £40,000, or over £50,000 for electric cars.

Historic vehicles made before 1 January 1986 are exempt under the rolling 40-year rule, but you must still tax them annually at £0.

Working out what you will spend on fuel

Running costs depend heavily on how and where you refuel or charge. As a reference point, UK average pump prices in the week commencing 14 September 2026 were 168.14 pence per litre for petrol and 190.72 pence per litre for diesel. Domestic electricity sat at 26.11 pence per kWh under the Ofgem price cap for 1 July to 30 September 2026, a national average for Direct Debit customers in England, Scotland and Wales.

A fuel cost calculator turns those figures into an annual or monthly number based on your own mileage. For electric cars, a typical mainstream model achieves roughly 3 to 4 miles per kWh in real-world driving, though this varies with temperature, speed and driving style. Home charging on an off-peak overnight tariff is usually cheaper than the price cap rate, while public rapid charging is usually considerably more expensive, so where you charge matters as much as what you drive.

Depreciation and the true cost of ownership

Depreciation is often the largest single cost of running a car, and it stays invisible until you sell. A depreciation calculator estimates how much value a car will lose over your intended ownership period, which is the figure that separates a cheap car from a good value one. A model that costs more up front but holds its value well can work out cheaper over three years than a cheaper car that drops sharply.

Add tax, fuel and depreciation together and you have a realistic annual cost. That total, not the purchase price, is what your budget has to absorb.

Comparing shortlisted cars

Once you have run the numbers on a few candidates, use compare vehicles to put them side by side. This is where the tools stop being separate calculations and start informing a decision: a car with higher tax but lower fuel costs, or one that depreciates slowly but costs more to insure, becomes easy to judge once the figures sit next to each other. Work through tax first, then fuel, then depreciation, and compare the totals before you commit.