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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?

Most petrol engines are made up of one or more cylinders, which work together to generate drive. You can read more about how an engine works in our guide.

The size of an engine is measured in cubic centimetres (cc) and refers to the total volume of air and fuel that’s pushed through the engine by its cylinders. 

For example, a 1,000cc engine has the capacity to displace one litre of this air-fuel mixture.

And sizes are almost always rounded to the closest hundred - a 1,020cc, for instance, would still be referred to as a 1.0-litre engine.

Generally, the bigger the engine the more powerful it is. However, many cars come with turbocharged engines, an addition that increases efficiency and power, which allow them to equal larger non-turbocharged ones.

Fuel cap

Does engine size affect fuel economy and insurance?

Larger engines, thanks to their greater capacity, generally use up more fuel than smaller ones. So it’s worth keeping this in mind if miles per gallon (mpg) is important to you.

What’s more, you’ll have to dip the accelerator more generously, burning up more fuel – making your motor less economical.

In terms of performance, top speed and acceleration will typically be better the more powerful, and bigger, an engine is.

This added power means the car could be deemed a greater "risk" in the eye's of an insurer, and so insurance premiums may rise as a result.

What engine size is right for me?

It all boils down to your needs and lifestyle.

If you’re a regular motorway commuter, for example, something more powerful, or turbocharged, may suit your needs better.

Whereas if you do a lot of driving around town, a car with a smaller engine might be preferable as they tend to be more efficient in these circumstances.

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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