Every car sold in the UK is assigned an insurance group from 1 (cheapest to insure) to 50 (most expensive to insure). Understanding how these groups work helps you make smarter buying decisions and avoid premium surprises.
How insurance groups are decided
Insurance groups are set by Thatcham Research on behalf of the Association of British Insurers. They are based on several factors: the cost of the car; the cost and availability of parts; how long repairs typically take; the performance of the car (higher performance means higher risk and higher group); the safety features fitted; and the car security rating.
Why insurance groups matter
The insurance group is one of the factors insurers use to set your premium. A car in group 1 will typically attract a significantly lower premium than the same driver in a group 40 car, all other things being equal. For younger drivers or those with limited no-claims history, the insurance group can make a larger difference to the annual premium than any other single factor.
How to check the insurance group of any car
The simplest way is to search the registration number or make and model on the Parkers or What Car websites, or use the Thatcham Research checker at thatcham.org. The information is publicly available and free to access.
Does modifying a car affect its insurance group
Yes. Modifications that increase performance (aftermarket exhaust, air intake, engine remaps, lowered suspension) can move a car into a higher insurance group and significantly increase premiums. Any modification must be declared to your insurer. Failing to disclose modifications can invalidate your insurance.
Group vs actual premium
The insurance group is a guide, not the final premium. Insurers apply their own algorithms that also consider your age, driving history, address, annual mileage, occupation, and many other factors. Two drivers in the same car in the same group can see very different premiums.
For any mechanical queries on a car you are considering buying, call Steins Garage on 0131 554 3423.