Every car sold in the UK is assigned an insurance group between 1 and 50. Group 1 is the cheapest to insure; group 50 is the most expensive. If you're buying a used car, the insurance group can make the difference between affordable cover and a quote that costs more than the car itself.
Here's how the system works and how to use it to your advantage.
How are insurance groups decided?
Insurance groups are set by the Group Rating Panel, which is made up of members from the Association of British Insurers (ABI) and Thatcham Research (the motor insurers' research centre). Every new car model is assessed and assigned a group based on several factors:
1. Repair costs
This is the biggest factor. Thatcham tests how much it costs to repair the vehicle after a standardised low-speed impact. Cars with expensive body panels, complex electronics, or parts that need specialist labour score higher.
2. Parts prices
The cost of common replacement parts — bumpers, headlights, windscreens, wings — directly affects the group rating. Cars with cheap, widely available parts score lower.
3. Performance
Engine power, top speed, and acceleration all influence the rating. Faster cars are statistically more likely to be involved in accidents, so they get higher groups.
4. Safety features
Cars with good safety ratings and advanced driver assistance systems (autonomous emergency braking, lane assist, etc.) can receive a lower group rating. Check a vehicle's safety credentials with our free car check — we include Euro NCAP ratings where available.
5. Security
Factory-fitted security features like immobilisers, alarms, and Thatcham-approved locking systems can reduce the group rating. Cars without an immobiliser may be bumped up.
6. Bumper compatibility
Thatcham tests whether the car's bumpers align with the standard European bumper height. Good alignment means less damage in low-speed impacts, which means lower repair bills and a lower group.
What the groups mean in practice
| Group Range | Typical Vehicles | Annual Premium (approx.) |
|---|---|---|
| 1–5 | Small city cars (Fiat 500, VW Up, Toyota Aygo) | £400–£800 |
| 6–15 | Family hatchbacks (Ford Focus, VW Golf, Vauxhall Astra) | £500–£1,200 |
| 16–25 | Larger saloons, SUVs, hot hatches (BMW 3 Series, Audi A3) | £700–£1,500 |
| 26–35 | Performance cars, premium SUVs (BMW M Sport, Audi S-Line) | £1,000–£2,500 |
| 36–50 | High-performance and luxury (Porsche, AMG, Range Rover Sport) | £1,500–£5,000+ |
These are rough guides — your actual premium depends on your age, location, driving history, and many other factors. But the insurance group sets the baseline.
How to check a car's insurance group
Before buying a used car, check its insurance group and get an actual quote. The best approach is:
- Run a free car check to confirm the exact make, model, variant, and engine size
- Look up the insurance group on Thatcham's website or comparison sites like GoCompare or Confused.com
- Get actual quotes before committing to a purchase — the same model with a different engine or trim can be in a very different group
The specific variant matters. A Ford Focus 1.0 EcoBoost might be in group 10, while a Focus ST with the 2.3-litre turbo engine could be in group 30+. Always check the exact specification.
Cheapest cars to insure (groups 1–10)
If you're looking for the most affordable insurance — especially for new or young drivers — these models consistently fall in the lowest groups:
- Fiat 500 1.0 — Group 3–6
- Volkswagen Up 1.0 — Group 1–3
- Toyota Aygo — Group 2–5
- Hyundai i10 — Group 2–5
- Vauxhall Corsa 1.2 — Group 4–8
- Ford Fiesta 1.0 — Group 5–10
- Nissan Micra 1.0 — Group 3–7
- Kia Picanto — Group 1–4
- Seat Ibiza 1.0 — Group 5–8
- Dacia Sandero — Group 3–7
These tend to be small cars with modest engines, cheap parts, and good safety features. Many also have low road tax costs and good fuel economy, making them affordable all round. If you're a new driver looking for an affordable first car, our first car checklist covers everything you need to consider.
How modifications affect insurance groups
Factory-fitted options don't change the insurance group. But aftermarket modifications can significantly increase your premium or even make the car uninsurable with some providers:
High-impact modifications:
- Engine remaps or turbo upgrades
- Larger alloy wheels
- Body kits and spoilers
- Performance exhaust systems
- Suspension modifications (lowering springs, coilovers)
Lower-impact modifications:
- Tinted windows (to legal limits)
- Dashcam installation
- Parking sensors
- Standard audio upgrades
You are legally required to declare all modifications to your insurer. Failing to do so can void your policy entirely, leaving you uninsured.
When buying a used car, check for modifications that the seller may not mention. Our guide to essential checks before buying a used car covers this and other important inspection points. Look for aftermarket exhausts, non-standard wheels, tinted windows, or any performance parts. These will affect your insurance even if the previous owner didn't declare them.
Tips for reducing insurance costs
Choose a car in a lower group
This is the most direct way to reduce your premium. If you're choosing between two similar cars, check the insurance groups and factor the difference into your running costs.
Build up no-claims bonus
Every claim-free year reduces your premium. Protect your no-claims bonus if your insurer offers it — it's usually worth the small extra cost.
Increase your voluntary excess
Agreeing to pay a higher excess (the amount you contribute in a claim) reduces the premium. But make sure you can actually afford the excess if you need to claim.
Consider black box insurance
Telematics (black box) policies monitor your driving and reward safe behaviour with lower premiums. These are especially effective for young drivers and can cut costs by 20–40%.
Park off-road
Parking on a driveway or in a garage rather than on the street reduces your premium. Insurers see off-road parking as lower risk for theft and accidental damage.
Pay annually
Monthly payments include interest that typically adds 15–30% to the total cost. If you can afford to pay the annual premium in one go, you'll save significantly.
The bottom line
Insurance groups are a useful shorthand for comparing the likely insurance cost of different vehicles. Always check the group before buying, and get actual quotes for the specific car you're considering.
Start with a free car check to confirm the exact vehicle specification, check its MOT history and mileage, then use that information to get accurate insurance quotes. A few minutes of research can save hundreds of pounds a year on your premium.