How to make sense of car insurance groups

We explain how it works so you can understand the factors that contribute to the insurance class your car belongs to

Car insurance classes
(Image credit: getty images)

Back in 2012, a rather unusual car was released – The Renault Twizy.

Despite it’s, um, modest power – a rip-snorting 17 bhp, since you ask – there were reports of early adopters getting car insurance quotes of around £800 a year. Quite a lot, all things considered.

It turned out that the dinky Twizy ‘quadricycle’ actually fell into Insurance Group 10, which typically contains vehicles with about five times as much power.

It didn’t seem to make much sense – you’d have to be pretty reckless to cause much damage in a Twizy, given its top speed was 50mph. It wasn’t even particularly expensive in the grand scheme of things to buy – a shade over £6,000. Although you’d expect as much given that it doesn’t have any doors.

So, how do insurers work out what car insurance groups vehicles fall into? Let's take a look.

Thatch the way (uh-huh uh-huh) I like it

Most insurance companies work to the Association of British Insurers’ 50 group system, which is derived from research from Thatcham – which, despite sounding like an artisanal cider manufacturer, is actually a motor insurance repair research centre, but that doesn’t quite roll off the tongue as well, does it?

However, some insurance companies have opted to ‘go rogue’ and use their own grouping system. Either way, the following factors are taken into account.

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How much would it cost to replace your vehicle if it was written off? This is, unsurprisingly, quite an important question for your insurance company.

Ergo, if your car is quite an expensive one, it’ll fall into a high insurance group.


Basically, how likely are you do damage in it? Insurers go on the logic that if a car goes fast, then you’re more likely to cause an accident in it – perhaps unfair considering that the faster a car is, the more stopping power it usually has in its brakes. But them’s the rules.


If parts for a car are cheap and plentiful, then it’ll cost less for your insurer to repair it. This is part of the reason why cars like, say the Ford Fiesta and Vauxhall Corsa occupy low insurance groups –  there are thousands of them on the roads and parts are abundant. Meanwhile, high-end supercars use bespoke, expensive parts. When they go wrong, they cost a lot to fix.

Incidentally, a car doesn’t necessarily have to be exotic or fast for it to be difficult to find parts for – the lack of bits and bobs for the Twizy was one of the reasons it figured in a high insurance group.


Is it going to be easy for a thief to get into to nick? If so, then it’ll have an influence on it being in a higher insurance group.

So, there you have it. THAT’S how your car insurance group is calculated.

Kristian Dando

A freelance personal finance journalist.