What is a car insurance group?

An advisory risk score from 1 to 50 for cars, produced by the Group Rating Panel and used by insurers as one input among many. It reflects the car, not the driver, and it is one of several factors that go into a quote rather than the quote itself.

Is group 1 the cheapest?

That is how the whole market works, but neither Thatcham nor the ABI publishes a sentence saying so. What Thatcham does publish is that the score indicates the level of insurance risk, and that its replacement scale runs from low risk upwards.

What do the letters after the group number mean?

They record how the vehicle performed against a benchmark set of security tests. Thatcham confirms the suffix exists but does not publish what each letter means, so the descriptions on this page are the settled industry convention rather than an official definition.

Does dropping two groups save much money?

Far less than most people expect. Postcode, claims history, age and annual mileage all move a premium more than the group does, and any modification can move it further than all of them.

Running costs

Insurance groups, and what they do not measure

The group is about the car. Almost everything that decides your premium is about you, which is why two people quoted on the same group 12 hatchback can be hundreds of pounds apart.

1 to 50

Groups for cars

Thatcham Research, Vehicle Risk Data (as of 7 September 2026)

21 to 50

Groups for light commercial vehicles

Thatcham Research, Vehicle Risk Data (as of 7 September 2026)

125

Data points reviewed per rating

Thatcham Research, Group Rating (as of 7 September 2026)

Checked on 7 September 2026.Thatcham Research, Group Rating (as of 7 September 2026)

What does a car insurance group mean?

It is an advisory risk score for the vehicle, from 1 to 50 for cars and 21 to 50 for vans. The Group Rating Panel produces it from the cost of repairing the car, its new price, its performance and the complexity of its standard fitted systems.

The output is advisory. Insurers take it as one input, apply their own rating factors on top, and arrive at a price that the group alone would never predict.

The four things the panel assesses

Group Rating assessment criteria
Criterion	What it covers
Cost	The repair strategy a car needs, and the cost and the time it takes to put it back to its original condition after a claim. Thatcham reviews a standard list of the most commonly damaged panels and components, so a car whose front bumper is cheap to replace rates better than one whose is not.
Price	The new price of the vehicle, trim level by trim level, because that is what an insurer settles at if the car is written off. Two cars of the same model can sit in different groups on price alone.
Performance	Nought to sixty time, weight and top speed. This is why the fastest version of a family hatchback is often ten or more groups above the entry engine.
Design	The complexity of the standard fitted systems, including security and active safety equipment. Autonomous emergency braking is assessed here, and its standard fitment and performance is one of the things the panel names explicitly.

The security suffix letters

Security suffix letters as the industry uses them
Letter	Meaning	Published by the rating body
E	Security exceeds the requirement for that type of car, and the vehicle moves down one group. A group 10 car rated E is shown as 9E.	No, industry convention
A	Security is acceptable for that type of car. The group is not adjusted.	No, industry convention
D	Security does not meet the required standard, and the group is increased by one.	No, industry convention
P	Provisional. Not enough security information was available when the model launched, so the rating is unconfirmed.	No, industry convention
U	The level of security is unacceptable. An insurer may require an upgrade before it will quote.	No, industry convention
G	A grey or parallel import, which does not carry a standard rating because the specification was not built for this market.	No, industry convention

Thatcham publishes that a suffix exists and that it reflects a benchmark set of security tests. It does not publish what each letter means. The descriptions above are consistent across the market and are labelled as convention rather than dressed up as an official definition.

What the group does not include

Your postcode, which is usually the single largest factor in a car insurance price.
Your age and how long you have held a licence.
Your claims history and any endorsements on your licence.
Annual mileage and what you use the car for.
Where the car is kept overnight.
Any modification, which insurers rate separately and often refuse outright.

What actually moves a premium

Average annual comprehensive premium quoted by age band
Age band	Average quoted
17 to 20	£1,813
20 to 29	£1,255
30 to 39	£850
40 to 49	£699
50 to 59	£552
60 to 69	£459
70 and over	£482

The spread between the youngest and the oldest band here is larger than the spread across the whole group scale. That is the point: the driver dominates the price, and the car is a smaller term than the marketing around insurance groups suggests.

Group Rating is being replaced

Thatcham is moving from the 1 to 50 Group Rating scale to Vehicle Risk Rating, which scores five separate assessments rather than producing one number.
The five are performance, damageability, repairability, safety and security, each scored from 1 for low risk to 99 for high risk.
Group Rating remains in use on existing models, so both scales are in circulation and a buyer comparing a new car to a five year old one will meet both.
Nothing in the change affects an existing policy. It changes what insurers are given, not what they charge you today.

Common questions

What is a car insurance group?: An advisory risk score from 1 to 50 for cars, produced by the Group Rating Panel and used by insurers as one input among many. It reflects the car, not the driver, and it is one of several factors that go into a quote rather than the quote itself.
Is group 1 the cheapest?: That is how the whole market works, but neither Thatcham nor the ABI publishes a sentence saying so. What Thatcham does publish is that the score indicates the level of insurance risk, and that its replacement scale runs from low risk upwards.
What do the letters after the group number mean?: They record how the vehicle performed against a benchmark set of security tests. Thatcham confirms the suffix exists but does not publish what each letter means, so the descriptions on this page are the settled industry convention rather than an official definition.
Does dropping two groups save much money?: Far less than most people expect. Postcode, claims history, age and annual mileage all move a premium more than the group does, and any modification can move it further than all of them.

Sources

No official body publishes a mapping from vehicle segment to group band, so this page does not carry one.