There's a number attached to every car sold in the UK that directly affects what you'll pay to insure it. It's called the insurance group, it runs from 1 to 50, and it's set before the car even goes on sale. Most buyers never check it until they've already committed — and occasionally discover the insurance costs more per year than the monthly finance payment. That's an avoidable problem, and this guide gives you everything you need to avoid it.
Who sets the groups — and how
Insurance groups are set by Thatcham Research, an independent organisation funded by the UK motor insurance industry. Thatcham's been doing this since 1971. When a new car model's launched, Thatcham assesses it before it goes on sale and assigns it a group. That group stays with the model unless Thatcham updates it — which can happen when a new variant's introduced or when repair cost data changes significantly.
The assessment covers six main factors:
- Repair cost: How expensive is the car to repair after a typical accident? Aluminium panels, complex sensor clusters embedded behind bumpers, and LED headlight assemblies all push repair costs — and groups — up. A car where a minor rear shunt triggers a £4,000 bumper and sensor replacement will sit significantly higher than one where the same impact costs £400.
- Parts prices: Thatcham prices a basket of 23 common parts. A car where the door mirror costs £400 sits higher than one where the same part costs £80. This is why premium marque cars sit higher even in their base forms — the parts are simply more expensive to source.
- Repair time: Labour time matters as much as parts cost. A car that takes six hours to straighten a sill sits higher than one that takes two. Modern cars with complex aluminium structures and sensors in every panel typically take longer.
- Performance: Acceleration and top speed. Faster cars are statistically involved in more serious accidents and cost more when they are. This is why the same hatchback in 1.0 and 2.0 GTI trim can sit fifteen groups apart.
- Security: Does the car have an immobiliser, Thatcham-approved alarm, and tracking device? Each layer of security reduces the group. Some manufacturers offer a security-enhanced variant at a lower group specifically to reduce insurance costs — worth knowing if you're choosing between specs.
- Bumper compatibility: Can the bumper absorb low-speed impacts without transferring damage to expensive components behind it? Cars that fail this test tend to be more expensive to repair in minor accidents, even small car park bumps.
The letter suffix: what E, D, U, A, and G mean
The group number is followed by a letter that tells you something important about the car's security relative to what Thatcham expected for that group. This suffix is often missed by buyers but it matters:
- E (exceeded): The car's security is better than Thatcham's requirement for that group. The insurer may rate it more favourably than the number alone suggests.
- A (acceptable): Security meets the requirement for the group. This is the standard outcome for most cars.
- D (provisional/descriptor): The car hasn't been fully assessed yet — common on very new models. Insurers treat D-rated cars with more caution, and some won't quote until a full assessment's complete.
- U (unacceptable): Security falls short of what's expected for the group. Some insurers refuse to quote; others add a significant loading. A U suffix is worth investigating before buying — it often means the car lacks an immobiliser or alarm that the group rating assumed it would have.
- G (grey import): The car was imported from outside the UK/EU and may have different specifications. Some insurers decline to quote grey imports entirely; others charge a significant loading.
What the groups look like in practice
Groups 1–10 are the territory of small-engined superminis and city cars. Hyundai i10, Citroën C1 1.0, Volkswagen Polo 1.0, Skoda Fabia 1.0 MPI, Nissan Micra 1.2. These are where first-time buyers should be looking if premium cost is a constraint. A driver under 25 will generally get their most competitive quotes on cars in this band.
Groups 11–20 cover a wide band — mainstream family hatchbacks in base or mid-spec trim, small diesels, and modestly powered crossovers. A Ford Focus 1.0 EcoBoost Trend Edition, a Vauxhall Astra 1.2, or a Nissan Juke 1.0 DiG-T typically sits in this band. These are reasonable everyday cars at a premium that's manageable for most drivers over 22 or 23 with a year of no-claims.
Groups 21–35 move into larger engines, executive cars, premium marques at lower specs, and performance variants of otherwise ordinary models. A BMW 1 Series 118i (Group 22–28), an Audi A3 2.0 TDI (Group 25–30), or a Ford Focus ST-Line X 1.5 EcoBoost 182 (Group 28–32) lands here. For a young driver, the gap between a Group 8 car and a Group 25 car in annual premium terms can be £1,500 or more.
Groups 36–50 are sports cars, high-performance saloons, prestige SUVs, and anything with significant power or a repair cost that reflects premium parts. These are cars where annual insurance for a young driver can exceed the car's purchase price by a wide margin. Even experienced drivers with full no-claims pay meaningfully more.
How the same model can span many groups
One thing that trips buyers up: they check the group for "a Golf" and find Group 12, then buy a Golf GTI without realising it's Group 34. The group's assigned at variant level, not model level. Trim, engine, and body style all matter separately.
A few examples of the spread within one nameplate:
- Ford Fiesta: 1.0 EcoBoost 100ps Trend = Group 8. 1.5 EcoBoost ST-3 = Group 26. Same badge, very different insurance cost.
- MINI Hatch: Cooper 1.5 = Group 14. John Cooper Works = Group 34.
- Volkswagen Golf: 1.0 TSI Life = Group 12. GTI Clubsport = Group 38.
Always check the specific engine and trim level, not just the model name.
Electric cars and insurance groups
EVs don't automatically sit in low groups just because they lack a traditional engine. In fact, most current EVs sit in higher groups than equivalent petrol cars, because repair costs are substantially higher: battery damage assessments, sensor-dense bumper assemblies, and specialist labour all contribute. A Nissan Leaf sits in Group 18–23 depending on year. A Kia EV6 is Group 30–40 depending on variant. The Renault Zoe is one of the better-placed EVs at Group 11–15, but that's still higher than a comparable petrol city car. If you're considering an EV partly because you assume it'll be cheaper to insure, check the group first — you may be surprised.
How to check any car's group
The Thatcham Research website (thatcham.org) has a free vehicle rating database. Enter the make, model, year, and engine variant to get the group. You can also use the DVLA's vehicle enquiry service with the registration plate, which returns the group alongside tax and MOT information.
More usefully for a buyer: most major comparison sites — Compare the Market, GoCompare, MoneySupermarket — allow you to enter a specific registration and get a quote before you commit. This is a soft search and won't affect your credit file. Doing this before you view a car takes five minutes and avoids the situation where you've already paid a deposit before discovering the insurance is £800 a year more than you expected.
What you can actually control
The group itself is fixed — you can't change it. What you can change:
- Add a named experienced driver. A parent or partner with 15+ years and full no-claims can reduce the premium significantly. This must reflect reality — fronting (naming someone as the main driver when they're not) is insurance fraud and voids the policy.
- Increase voluntary excess carefully. A higher excess reduces the premium but means you pay more if you claim. Don't set it higher than your emergency fund can cover.
- Telematics/black box insurance. For drivers under 25, a telematics policy can halve the premium compared to a standard policy on the same car. See the guide on black box and telematics insurance for a full breakdown.
- Mileage. Declaring a realistic annual mileage — not inflating it "just in case" — reduces the premium. If you drive 4,000 miles a year, don't say 8,000.
- Security upgrades. Adding a Thatcham-approved tracker or alarm to an older car without factory security can reduce the effective group the insurer rates it at. Check with thatcham.org before buying any aftermarket device.