How are car insurance groups decided?

By Insurance Group Checker Editorial TeamReviewed by Motoring Data DeskLast updated 16 September 2026

Quick answer

UK car insurance groups are set by the Group Rating Panel — ABI and Lloyd's Market Association members, using testing from Thatcham Research. Each new car and derivative is scored on repair cost, parts prices, new-car value, performance, safety, security and damageability, then placed in a group from 1 to 50.

Who actually makes the decision

It isn't an insurer, and it isn't the government. UK insurance groups are assigned by the Group Rating Panel, an industry body whose members come from the Association of British Insurers and the Lloyd's Market Association. The panel meets regularly to assign ratings to newly launched models and to each new derivative of an existing one.

The panel doesn't do the testing itself. Thatcham Research — the motor insurers' automotive research centre — carries out the crash, repair and security work that the decisions rest on: standardised damage tests, measured repair times, parts pricing, and theft-resistance assessments. The panel then turns that evidence into a number.

One thing worth knowing: the rating is advisory. Insurers aren't obliged to use it. Most treat it as a shared starting point and then layer their own claims experience on top, which is a large part of why two insurers quote such different prices for the same car.

The factors behind every rating

The panel assesses around fifteen criteria. They aren't weighted equally — repair economics dominate, because that's what most claims actually cost.

Repair cost and repair time

The single biggest driver

Most insurance claims are low-speed damage, not write-offs — so what it costs to put a car right matters more than almost anything else. The panel looks at standardised repair times for common damage, paint and labour hours, and whether a repair needs specialist equipment or an approved bodyshop.

Parts prices

Heavily weighted

The cost of the parts a bodyshop actually orders — bumpers, headlamps, wings, radiators, sensors. Two cars of similar size can rate very differently if one has cheap, widely-stocked parts and the other has scarce, manufacturer-only components.

New car value

Significant

The list price sets the insurer's worst-case exposure on a total loss. It's why an expensive car rarely lands in a low group even when it's slow and safe.

Performance

Significant

Acceleration, top speed and power relative to weight. Faster cars crash harder and more often, so performance moves the rating up sharply — which is why the same bodyshell can span twenty-plus groups between its base engine and its hot version.

Safety and crash-avoidance technology

Pulls the rating down

Autonomous emergency braking and similar systems reduce the number and severity of claims, so strong safety specification works in a car's favour. This is one of the few factors that actively lowers a group.

Security

Can move it sharply

How well the car resists theft, tested by Thatcham. Vulnerability to keyless relay attacks has pushed several otherwise-ordinary models up the scale in recent years, and strong security pulls them back down.

Bumper alignment and damageability

Technical but real

Whether bumpers line up with other cars in a low-speed shunt, and whether impact energy is absorbed by cheap sacrificial parts or transmitted into expensive structures behind them.

Why the same car can span twenty groups

Ratings are assigned per derivative, not per model name — and that is the single most misunderstood thing about the system. A family hatchback with a small turbo engine and a hot version of the same car share a shell, a badge and a showroom, but they are rated as different vehicles because their performance, parts and repair complexity genuinely differ.

You can see this clearly across our model pages: the VW Golf spans roughly twenty-seven groups from its entry engine to the R, and the Ford Focus behaves the same way once you reach the ST. Searching for a model name alone will always give you a misleadingly wide answer — the trim is the thing that matters.

What doesn't affect the group

Plenty of things people assume are factors genuinely aren't. Your age, postcode, job, claims history and annual mileage don't touch the group at all — they affect your premium, which is a different calculation entirely. Nor does the car's colour, its road-tax band, or whether you park it on a drive. The group describes the vehicle; everything about you is priced separately, as we explain in how your group affects your premium.

How the system is changing

The 1–50 scale was designed for a simpler era of cars. Driver-assistance sensors in bumpers, bonded aluminium structures, EV battery packs and keyless entry have all changed what damage costs and how cars get stolen. Thatcham's answer is the Vehicle Risk Rating framework, which scores new model ranges from August 2024 on five separate pillars instead of one blended number.

For now, both run alongside each other — the vast majority of cars on UK roads still carry a classic group, which you can check by registration or look up in our full 1–50 groups list.

Frequently asked questions

Who decides car insurance groups in the UK?

The Group Rating Panel, which is made up of members from the Association of British Insurers (ABI) and Lloyd's Market Association, with technical research and testing provided by Thatcham Research. The panel meets regularly to assign a group to new models and derivatives.

What is the Group Rating Panel?

It's the industry body that assigns every new UK car a group from 1 to 50. It's advisory rather than binding — insurers aren't obliged to use the number — but in practice it's the common reference point the whole market works from.

What is Thatcham Research?

Thatcham Research is the motor insurers' automotive research centre. It carries out the crash, repair and security testing that feeds the panel's decisions, and it also runs the newer Vehicle Risk Rating framework that is gradually replacing the 1–50 scale.

What factors affect insurance group rating?

Repair cost and repair time, parts prices, new car value, performance, safety and crash-avoidance technology, security against theft, and damageability factors like bumper alignment. Repair cost and parts prices do the heaviest lifting.

Does engine size affect the insurance group?

Indirectly. Engine size itself isn't scored — performance is. A larger engine usually means more power and faster acceleration, which is what actually raises the rating. A big but low-output engine can rate below a small, highly-tuned one.

How often are insurance groups updated?

The panel meets regularly to rate newly launched models and derivatives, so new cars are added continuously. An existing model's group is effectively settled once assigned — it's the newer Vehicle Risk Rating framework that is designed to be revisited over a car's life.

Do insurers have to use the group rating?

No. Group ratings are advisory. Most insurers use them as a starting point and then apply their own claims data on top, which is part of why quotes for the same car vary so much between providers.

Why do two versions of the same car have different groups?

Because ratings are assigned per derivative, not per model name. Different engines, trim levels, wheel sizes and safety packs change performance, parts cost and repair complexity — so the panel rates each variant separately.

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Sources & further reading

Thatcham Research — The motor insurers' automotive research centre. Co-runs the Group Rating Panel that sets UK insurance groups, and publishes the Vehicle Risk Rating (VRR) framework.
Association of British Insurers (ABI) — The trade body for UK insurers. Co-runs the Group Rating Panel behind the 1–50 insurance group scale.
DVLA — Get vehicle information — The official GOV.UK service for vehicle details by registration. Our checker uses the DVLA's Vehicle Enquiry Service API, the same underlying record.