Car insurance groups explained: how your car affects your premium

When you get a car insurance quote, one factor sits quietly behind the price: the car's insurance group. Every car sold in the UK is placed in a group from 1 to 50, and it can make a striking difference to what you pay. This guide explains car insurance groups, how they are decided, and how to use them to keep your premium down.

What car insurance groups are

Insurance groups are a way of ranking cars by how much they are likely to cost an insurer. Every car is assigned a group from 1 to 50, where group 1 is the cheapest to insure and group 50 the most expensive. When you choose a car, you are also, in effect, choosing a starting point for your premium, which is why the group is worth checking before you buy.

Who decides the groups

The groups are recommended by a panel that reviews vehicle data, with research carried out by Thatcham Research on behalf of the insurance industry. They look at a range of measures for each car and agree a group rating. Insurers then use that group as one input into their own pricing, alongside everything about you as a driver, as explained in our guide to how premiums are calculated.

What affects a car's group

Several features push a car up or down the scale. The cost of repairs and the price of parts matter a great deal, as does how long repairs take. Performance counts too, since faster, more powerful cars tend to be involved in costlier claims. The car's value when new, the cost of a replacement, and the security features fitted, such as alarms and immobilisers, all feed in. Safer, cheaper-to-repair cars sit in lower groups.

How much difference it makes

The difference between groups can be large. A small city car in group 1 to 5 can cost a fraction of what a powerful car in the higher groups costs to insure, sometimes a difference of hundreds or even thousands of pounds a year, especially for younger drivers. For an experienced driver the gap is smaller but still real. Either way, the group is one of the biggest factors you control.

Using groups to save money

If keeping your premium low is a priority, choosing a car in a low insurance group is one of the most effective steps you can take, as set out in our guide to lowering your car insurance. Before buying, look up the group for the exact model and trim, because different versions of the same car can sit in different groups depending on engine size and specification.

Groups are not the whole story

It is important to remember that the group is only a starting point. Two drivers in the same car can pay very different prices because of their age, postcode, history and the other factors insurers weigh. A low-group car will not make a high-risk driver cheap on its own, but it gives everyone a better starting position. Think of the group as the foundation, not the final price.

Electric cars and groups

Electric cars often sit in higher groups than you might expect, because their batteries and technology can be costly to repair, as covered in our guide to electric car insurance. As repair networks mature this is gradually easing, but it is worth checking the group of any electric car before assuming it will be cheap to insure simply because it is small or economical to run.

Checking a car's group before you buy

You can check a car's insurance group before buying through most comparison sites, manufacturer information, or motoring guides. If you are choosing between two similar cars, comparing their groups can reveal a meaningful difference in running costs that is easy to miss when you focus only on the purchase price. A slightly cheaper car to buy can be more expensive to insure, and vice versa, so it pays to look at the whole picture.

Why the same model can sit in different groups

It is worth knowing that two versions of the same model can fall into different insurance groups. A larger engine, a higher trim level, or a sportier variant can push a car several groups higher than the basic version, because performance and value rise with it. So when you check a group, check it for the exact engine and specification you are considering, not just the model name, or the figure you rely on may be wrong.

Security can move a car down

Security features influence the group too. Cars fitted with good alarms, immobilisers and tracking are less attractive to thieves and can sit in lower groups as a result. If you are choosing between versions, the better-protected one may be cheaper to insure. You should not usually fit non-standard security yourself without telling your insurer, since any change from standard counts as a modification that must be declared.

Insurance is one cost among several

Finally, weigh the insurance group alongside the other costs of running a car, such as fuel or charging, tax, servicing and depreciation. A car that is cheap to insure but costly to run, or vice versa, may not be the bargain it first appears. Looking at the whole picture, with the group as one important piece, gives you the truest sense of what a car will cost to own.

Do groups change over time?

Insurance groups are not fixed forever. New models are assigned a group when they launch, and existing ratings can be reviewed as more is learned about how a car performs in the real world, including its repair costs and theft record. That means the group for a particular model can shift between versions and over the years. When you are checking, use a current source for the exact car and year you are looking at, rather than relying on a figure you remember from a while ago, so the price you expect matches what you will actually be quoted.

In practice, the simplest habit is to check the insurance group of any car you are seriously considering, for the exact engine and trim, before you decide. It takes a moment and can save you a great deal over the years you own the car.

In short

Every UK car is rated from group 1 (cheapest to insure) to 50 (most expensive), based on repair and parts costs, performance, value and security, with research by Thatcham Research. The group is one of the biggest factors you control, so checking it before you buy, and favouring lower groups, is a simple way to keep premiums down. It is a starting point, though, not the final price.

Where to get help and next steps

To put this to use, read how to lower your car insurance and how premiums are calculated. If you are choosing a policy as well as a car, our guide to the types of cover explains the levels available.