The price on the windscreen is the number people look at. The number that decides whether a car works for you is the monthly cost of keeping it. A cheaper car with high insurance and thirsty fuel use can cost more each month than a dearer car that is cheap to run.

This guide shows what to include and where to get real figures. We do not give average costs here, because your insurance, your mileage and your car change everything. Use your own numbers in the free running cost calculator.

Start with your mileage

Everything else follows from how far you drive. Look at a normal month: commuting, school runs, shopping, visiting family, and the odd long trip. If you have an old MOT certificate or service receipt, the mileage history on the free MOT history checker (opens in a new tab) shows how far your current car does in a year.

Fuel

Fuel is usually the biggest running cost. To work it out:

1. Take your monthly miles. 2. Divide by the car's real-world miles per gallon. 3. Multiply by 4.546 to turn gallons into litres. 4. Multiply by the price per litre at your usual garage.

The official MPG figure in a brochure is often higher than real driving gets, especially for short journeys in town. Owner forums and reviews for the exact model give a more honest figure.

Insurance

Insurance varies more than any other cost. Your age, postcode, driving history, job, and the car's insurance group all matter. Before you buy, get real quotes for the exact car. Use the registration if you can. Two cars at the same price can be very different to insure.

Road tax

Vehicle tax (VED) depends on when the car was first registered:

  • Cars first registered between March 2001 and March 2017 are taxed by their CO2 emissions band.
  • Cars first registered from April 2017 pay a standard yearly rate, plus an extra charge for five years if the list price was high when new.

The rates change, so use the GOV.UK vehicle tax rate tables (opens in a new tab) for the exact figure. Remember that tax does not transfer when you buy a car. You need to tax it yourself before you drive away.

MOT, servicing and repairs

Most cars over three years old need an MOT every year. The maximum official fee for a car is £54.85, and many test centres charge less.

Servicing and repairs are harder to predict. A sensible approach is to set aside a fixed amount each month for repairs, so a bill does not arrive all at once. Older, higher-mileage cars need a bigger pot. Read the MOT history: repeated advisories for tyres, brakes or corrosion tell you what is likely to need money soon.

Do not forget tyres. A full set is a real cost, and the MOT history often shows when they were last close to the limit.

Parking, permits and the LEZ

In Glasgow, parking can be a real monthly cost. Residents' permits, workplace parking and city centre car parks all add up. Include whatever applies to you.

If you will drive into the city centre, check the car meets the Low Emission Zone standard on the Scottish LEZ checker (opens in a new tab). A car that does not meet it can lead to penalty charges, and those rise for repeat entries. There is more detail in our Glasgow LEZ guide.

Breakdown cover and the small things

Breakdown cover, screen wash, car washes, and the occasional bulb or wiper blade are small on their own. Together, they are worth a line in your budget.

Put it together

Add all of the monthly figures. Then add the cost of the car itself spread over the time you expect to keep it, minus what you think you might sell it for at the end. That gives you a truer cost per month than the price alone.

When you compare two cars, run the same sums for both. You may find the cheaper car is not the cheaper choice.

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