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Jamie Gibbs

Car engine sizes explained


We explain the difference between varying engine sizes, and the impact on fuel economy and performance.

Car engine

Usually before you buy a car you look at the different models, trim levels and optional extras. Perhaps you’ll also take into consideration the cost of VED (Vehicle Excise Duty), depreciation, insurance and a car’s fuel economy.

But one of the more puzzling things is understanding the variety of engine sizes, their differences and the jargon around them.

What do engine sizes actually mean?

An engine’s size is measured in cubic centimetres (cc) and refers to the total volume that’s displaced by all cylinders in the engine altogether. If you’re not sure what this means, see our guide on how an engine works.

Each piston’s combined capacity to displace a mixture of air and fuel makes the total size of the engine. For example, a 1,000cc engine has the capacity to displace one litre of volume.

Sizes are almost always rounded up to the closest hundred, for instance a 1,020cc would still be referred to as a 1.0-litre engine. Another example is a 2,211cc engine – this one would be 2.2 litres.

Passenger cars come with engines equipped with up to 12 cylinders, and a minimum of two.The more cylinders, the bigger the capacity and the bigger the engine. Size is a good indication of how powerful an engine is.

However, a bigger engine doesn’t always mean it’s more powerful. Many cars come with turbocharged engines which allow them to equal larger non-turbocharged ones. The turbocharger is an engine add-on which increases efficiency and power by partly reusing exhaust gases that are normally lost.

An engine’s power is measured in brake horsepower (bhp). For example, a diesel 1.4-litre Ford Fiesta can return around 70 bhp.

Fuel cap

Does engine size affect fuel economy and insurance?

Larger engines are generally thirstier because they have greater capacity and use up more fuel than smaller ones. It’s worth keeping this in mind if miles per gallon (mpg) is important to you.

Generally speaking, if you’re a regular motorway commuter, you should go for something more powerful or smaller and turbocharged. Cars with smaller engines are more efficient around town, but at motorway speeds they may struggle to keep with traffic.

What’s more, you’ll have to dip the accelerator more generously, burning up more fuel – making your motor less economical. Automakers tend to test cars’ mpg in closed environments, and usually real-life results can be different. That said, they can still be a very good starting point when researching which cars to buy.

In terms of performance, cars with smaller engines are less powerful. Meaning, top speed and acceleration will be better the more powerful and bigger an engine is. This added power means the car is a greater risk, and so insurance premiums may rise as a result.

Plus, there might be significant differences in both efficiency and performance when comparing cars of different ages but with similar engine specification.

What engine size is right for me?

It all boils down to your needs and lifestyle. Think of the reason you need a car – is it to commute to work every day? Or to travel long distances and maybe fit your family in comfortably? Or perhaps you just need to go with something balanced that offers a nice blend of performances and fuel efficiency.

That said, engine size shouldn’t be the main factor you base your choice on. It’s just one of the many factors that come into play.

Think of the bigger picture, and remember that reliability, safety, comfort and running costs are just as important.


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