Car Insurance Groups Explained: What They Mean for Your Premium

Car insurance groups are a rating system that ranks every car model on a scale of 1 to 50 based on how much risk it presents to insurers. The lower the group, the cheaper the car tends to be to insure. The higher the group, the more you'll generally pay.

The system is managed by Thatcham Research, an independent automotive research centre that assesses vehicles on behalf of UK insurers. You might also see references to the ABI (Association of British Insurers) — they originally created the group rating system, but Thatcham now handles the day-to-day assessments through the Group Rating Panel.

Every new car that goes on sale in the UK gets assessed and assigned a group before it hits showrooms. Used cars keep the group rating of the model and spec they were when new. It's worth noting that different trim levels, engine sizes, and even gearbox options within the same model can sit in different groups — so a Ford Fiesta 1.0 EcoBoost might be in group 10, while the 1.5 ST version could be in group 26.

You can check your car's group using our free car insurance group checker.

Thatcham Research evaluates each vehicle across several criteria. None of these factors work in isolation — they're combined into an overall risk profile that determines the final group rating.

Here's what goes into the assessment:

• Damage and parts costs — How much does it cost to source replacement panels, bumpers, headlights, and other body parts? Cars with expensive or hard-to-find parts land in higher groups.
• Repair times — A car that takes 15 hours of labour to fix after a typical collision costs more to claim on than one that takes 5 hours. Aluminium body panels and complex electronics push repair times up.
• New car value — More expensive cars cost more to replace if written off, so they tend to sit in higher groups.
• Performance — Top speed and acceleration (0-62mph time) are factored in. Faster cars are statistically more likely to be involved in serious accidents.
• Safety features and crash test ratings — Vehicles with high Euro NCAP ratings, autonomous emergency braking (AEB), and advanced driver assistance systems (ADAS) can receive a lower group rating, because they're less likely to be in a serious crash — or more likely to reduce injury severity.
• Security features — Thatcham also rates vehicle security. Cars with approved immobilisers, alarm systems, and strong resistance to keyless theft score better. This is especially relevant now, given the rise in relay attacks on keyless entry cars.

Thatcham publishes their assessments through the Group Rating Panel, which includes members from the ABI and Lloyd's Market Association (LMA). Insurers aren't obligated to follow the group ratings exactly, but the vast majority use them as a starting point for pricing.

Here's a practical breakdown of what each group range typically includes. Bear in mind that specific models shift groups when Thatcham updates their assessments, so always check the current group for any car you're considering.

The quickest way is to use our car insurance group checker. It'll show you the group for any car model sold in the UK, along with what that means for your likely premium.

You can also check directly with Thatcham Research, who maintain the official database. Their website lets you search by make and model to see the current group rating along with the detailed breakdown of how it was assessed.

If you're buying a used car, the group rating is based on the original specification — not the car's age or current value. A 10-year-old BMW M3 is still going to be in a high group even if it's worth a fraction of its new price, because the repair costs and performance characteristics haven't changed.

The relationship is straightforward: higher group usually means higher premium. But your car's group is just one piece of the puzzle. Insurers also weigh up:

• Your age and driving experience — younger drivers pay more regardless of the car
• Where you live — urban postcodes with higher theft and accident rates attract higher premiums
• Driving history — claims, convictions, and penalty points all push costs up
• Annual mileage — more time on the road means more exposure to risk
• No-claims discount — each claim-free year earns a discount that can slash your premium by up to 70%
• Voluntary excess — choosing a higher excess lowers your premium

This means two cars in the same insurance group can cost very different amounts to insure depending on who's behind the wheel. A group 5 car might cost a 40-year-old with 15 years' no-claims about £350 a year, while the same car could cost an 18-year-old without any no-claims over £1,500.

The most effective approach is to compare car insurance quotes for the specific car you're considering, rather than relying on the group number alone.

If you're buying a car and want to keep insurance costs down, here are some of the cheapest models to insure in the UK right now. These all sit in groups 1-5.