Car Insurance Groups UK: How Groups 1 to 50 Affect Your Premium

What car insurance groups are

Every new car model sold in the UK is assigned an insurance group on a scale of 1 to 50. The principle is simple: the lower the group number, the cheaper the car tends to be to insure, and the higher the number, the more expensive. A small city car with a modest engine usually sits in a low group, while a high-performance or luxury vehicle sits near the top of the scale.

The group system gives insurers a consistent starting point for comparing the relative risk and cost of insuring different vehicles. It is not a price in itself, but a rating that feeds into each insurer's own pricing model alongside details about the driver and where the car is kept.

Because the scale runs to 50, two cars in adjacent groups may differ only slightly, while a car in group 5 and a car in group 45 will typically show a large difference in premium for the same driver.

Who decides the groups

Insurance group ratings are recommended by the Group Rating Panel, an industry body whose work is administered by Thatcham Research in conjunction with the Association of British Insurers. The panel reviews research on each vehicle and recommends a group, which insurers then use as guidance.

The system is advisory rather than mandatory. Insurers are not legally bound to follow the recommended group, and they remain free to set their own prices using their own data. However, the group rating provides a widely recognised benchmark that most of the market refers to.

The panel meets regularly to assign groups to new models and to review existing ones, so a car's group reflects up-to-date research on repair costs and safety performance rather than a one-off judgement.

What goes into a group rating

Several technical factors determine where a car sits on the scale. The main inputs include:

• Cost of repairs: how expensive the car is to fix after a typical accident, including labour time.
• Parts prices: the cost and availability of common replacement parts, measured against a standard basket.
• New car value: the price of the car when new, which influences the cost of a total-loss settlement.
• Performance: the car's power and acceleration, since higher performance is associated with greater claim risk.
• Security: the standard of fitted security such as alarms, immobilisers and locking systems.
• Body shell and repair times: how the structure behaves in low-speed impacts and how long repairs take.

Strong security features can pull a car into a lower group, while high performance or costly parts push it higher. This is why two cars of similar size can sit in noticeably different groups.

How the group feeds into your premium

The insurance group is only one element of the price you are quoted. The FCA-regulated insurer combines it with personal rating factors such as your age and driving experience, claims and convictions history, the postcode where the car is kept, your annual mileage and your no claims discount.

This is why a low-group car does not guarantee a low premium for everyone. A new driver in a high-risk area may still pay a substantial amount to insure a group 5 car, while an experienced driver with a long no claims record may pay relatively little to insure a car in a higher group.

Because each insurer weights these factors differently, quotes for the identical car and driver can vary significantly. The group sets the relative starting point, but the final price is the insurer's own calculation.

Choosing a car with the group in mind

For buyers focused on running costs, checking the insurance group before purchase can avoid an unwelcome surprise. A car two or three groups lower can make a meaningful difference to the premium, particularly for younger drivers or those with limited claims history.

Trim level and engine size matter: the same model can span several groups depending on the variant. A higher-powered or more heavily equipped version of a car will usually sit in a higher group than the entry-level option, so the specific variant should be checked rather than just the model name.

Adding non-standard modifications can also affect the rating an insurer applies, because they alter repair cost, performance or theft risk, and they must be declared. Undeclared modifications can lead to a refused claim under disclosure rules.

Common misunderstandings about groups

A frequent misconception is that the insurance group is the same as a tax band or emissions rating. It is not: the group reflects insurance risk and repair cost, not fuel economy or vehicle tax. A clean, efficient car can still sit in a high insurance group if it is powerful or expensive to repair.

Another misunderstanding is that the group alone sets the price. As explained above, the group is guidance that insurers combine with personal factors, so the same group can produce very different premiums for different people.

Finally, the groups are not fixed forever. As repair costs, parts prices and security standards change, the Group Rating Panel can revise a model's group, which is one reason long-standing cars may be re-rated over time.

Frequently asked questions

What is the cheapest car insurance group?

Group 1 is the lowest of the 50 groups and is generally associated with the cheapest cars to insure, typically small cars with modest engines and good security. The price you actually pay still depends on your personal rating factors.

Who sets insurance groups in the UK?

The Group Rating Panel recommends the groups, with the work administered by Thatcham Research alongside the Association of British Insurers. Insurers use the recommended group as guidance rather than a fixed rule.

Does a low group guarantee a low premium?

No. The group is only one factor. Your age, location, claims history and no claims discount all affect the final price, so a low-group car can still be costly for a high-risk driver.

Can the same model be in different groups?

Yes. Different engine sizes, trim levels and specifications of the same model can fall into different groups, so the specific variant should be checked before buying.

Do modifications change my insurance group?

Modifications do not change the official group, but they can change the rating and price an insurer applies, because they affect repair cost, performance or theft risk. They must be declared to avoid a refused claim.