How we score cars

The score is a weighted average of up to six categories, each marked out of 10 from published data. Two of them, running costs and emissions, are scored by percentile like for like: against cars of the same class and the same powertrain, so a petrol supermini is measured against petrol superminis, not against the whole market.

If a category cannot be scored because a figure is missing, it is left out and its weight is shared across the categories that remain. We never fill a gap with a guess.

It would not be fair to rank a city car's running costs against a large SUV's, nor to rank a petrol car's against an electric one, so for the two percentile categories we compare each car only with others of the same class and the same powertrain. We place every car into one of a small, fixed set of UK classes using a published map from the official make and model, which we keep deliberately conservative: a model we cannot place with confidence is simply left out of the comparison rather than guessed at. Powertrains are petrol, diesel, hybrid (mild or full), plug-in hybrid and electric.

This keeps the categories honest and avoids double counting. A petrol car is not marked down on running costs and emissions just for being petrol while electric and hybrid rivals sit in the same list; instead, the advantage of going electric shows up where it actually lands, in company car tax and in the breadth of powertrain choice. Running costs still exclude plug-in hybrids, whose official figures assume constant charging.

We compare against a group only when it has at least 25 different models in the official data. If the same-powertrain group is smaller than that, we widen to the whole class; if the class is still too small, or we could not place the car, we fall back to every new car on sale. The car page always says which, in the figure: "of petrol superminis on sale", or "of superminis on sale", or "of new cars on sale". Company car tax, practicality, performance and powertrain choice are not class-relative: they use the fixed scales below.

The classes

• city car
• supermini
• small family car
• executive car
• small SUV
• mid-size SUV
• large SUV
• sports car
• MPV

Running costs and company car tax carry the most weight because they are the figures that differ most between cars and matter most to the money side of a lease. The weights are fixed and the same for every car.

How it is scored. Fuel or charging cost in pence per mile at current UK prices, then ranked against cars of the same class and the same powertrain (petrol against petrol, hybrid against hybrids). Score is the percentile: a car cheaper to fuel than 70% of that group scores 7.0. Petrol is 175.3p and diesel 200.0p a litre (latest UK average), electricity 26.32p per kWh charged at home.

Which engine. The entry (lowest-powered) petrol, diesel, hybrid or electric engine, the one most drivers choose. Plug-in hybrids are left out.

How it is scored. The lowest benefit-in-kind percentage available in the range for the 2026/27 tax year, turned into a score of 10 minus (the percentage minus 3) divided by 3.4, capped between 0 and 10. So a 4% electric car scores about 9.7 and a 37% car scores 0.

Which engine. The engine with the lowest benefit-in-kind percentage in the range, the best choice for a company car driver.

How it is scored. Official WLTP CO2 in g/km, ranked against cars of the same class and the same powertrain (lower is better). Score is the percentile: lower than 60% of that group scores 6.0. A fully electric engine counts as 0 g/km.

Which engine. The same entry engine as running costs, so the figure reflects the typical car rather than the greenest or the fastest version.

How it is scored. The standard, seats-up boot in litres, read from the official specification. Score is (litres minus 150) divided by 55, capped between 1 and 10, so a 400-litre family hatchback scores about 4.5 and a 600-litre estate about 8.2.

Which engine. Not engine specific: the car's standard boot.

How it is scored. The quickest 0 to 62 mph time in the range. Score is 10 minus (the time in seconds minus 4) times 0.8, capped between 1 and 10, so 4.0 seconds or quicker scores 10 and around 11 seconds scores about 4.

Which engine. The quickest engine in the range (the shortest 0 to 62 mph time).

How it is scored. How many distinct powertrains the range offers across petrol, diesel, hybrid, plug-in hybrid and electric. One scores 4, two score 6.5, three score 8, four score 9 and five score 10. A mild hybrid counts under petrol or diesel, not as a separate hybrid.

Which engine. All engines, counted by powertrain type.

Each category score is multiplied by its weight, the results are added up and divided by the total weight of the categories that were scored, then rounded to one decimal place. Because the divisor is the weight actually used, a car with one category missing is not punished for the gap: the remaining categories simply carry more of the total.

Every car page shows the overall score and each category's mark next to the figure it came from, for example "0-62 mph in 6.5s" or "129 g/km, lower than 48% of petrol small family cars on sale", so you can see the number behind the mark.

Power, fuel economy and CO2 come from the Vehicle Certification Agency (VCA), the UK government's official source, which also gives us the full list of every new car on sale for the percentile comparisons. Torque and 0 to 62 mph times, where the VCA does not publish them, come from the manufacturer. Fuel prices are the latest UK average pump prices, electricity is the Ofgem price cap (1 October to 31 December 2026), and tax rates are the current HMRC and gov.uk figures.

Each source, the licence it is used under and the attribution it requires are listed in full on our data sources page.

The score is calculated fresh every time a car page is served, so it moves on its own as the inputs change: fuel prices update weekly, the Ofgem electricity cap each quarter, and tax rates each tax year. We do not re-write scores by hand, which is what keeps them consistent from one car to the next.

The score only measures things we can take from official data. It does not try to rate comfort, interior quality, reliability, how a car drives or what a dealer is like, because we have no consistent, published data for those, and inventing marks for them is exactly what we are avoiding.

• Economy and CO2 are WLTP lab figures, meant for comparing cars, not a promise of real-world results.
• Plug-in hybrid economy and CO2 are the official weighted figures, which assume the battery is charged regularly. On a flat battery the real figures are much worse, so we leave plug-in hybrids out of the running-cost category.
• We do not hold each plug-in hybrid's electric-only range, so for company car tax they are scored on the lowest range band, a deliberately cautious assumption.
• List price is not part of the score. Whether a car is good value at its monthly cost depends on the deal in front of you, which is not something we publish.

Alongside the score, each car page carries a short written "Our view". That is our editorial take, kept clearly separate from the data score and never used to move a number. The score is the data; the view is the words. You can read more about how we research and write on our about page.