Car Insurance Groups Explained: What They Mean for UK Buyers

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. Understanding these groups is one of the most practical things you can do before buying a car, because the group your car sits in directly affects how much you pay for insurance every single year.

For new and young drivers, the difference between a group 5 car and a group 25 car can easily be £1,000 or more per year in premiums. Even for experienced drivers with full no-claims discount, the insurance group still plays a significant role in what you pay.

1. What Are Insurance Groups?

Insurance groups are a standardised rating system that categorises every car sold in the UK on a scale from 1 to 50. The system is managed by the Group Rating Panel, which includes members from the Association of British Insurers (ABI) and the Lloyd's Market Association (LMA).

The research behind the ratings is carried out by Thatcham Research, the motor insurers' automotive research centre. Every new car that goes on sale in the UK is assessed and assigned a group before it reaches showrooms.

Insurers are not legally required to follow the group ratings, but the vast majority use them as a baseline when calculating premiums. A car in group 3 will almost always be cheaper to insure than a car in group 30, all else being equal.

2. How Are Insurance Groups Decided?

The Group Rating Panel considers several key factors when assigning a car to a group:

• Damage and parts costs — How expensive is the car to repair after an accident? Cars with cheap, widely available parts score better
• Repair times — How long does it take to fix? Longer labour times mean higher claims costs
• New car value — More expensive cars cost more to replace, pushing the group up
• Performance — Engine power, acceleration, and top speed all affect risk. Faster cars are in higher groups
• Safety features — Cars with advanced safety tech (autonomous emergency braking, lane assist) can be rated lower
• Security — Factory-fitted alarms and immobilisers improve the rating. Thatcham security ratings are a key input
• Bumper compatibility — Cars designed to minimise damage in low-speed impacts score better

3. How to Check a Car's Insurance Group

There are several free ways to check the insurance group of any car:

• Thatcham Research — The official source at thatcham.org. Search by make, model, and variant
• Comparison sites — When you get a quote on Compare the Market, GoCompare, or Confused.com, the insurance group is usually displayed
• Parkers or What Car? — Both list insurance groups in their car specifications pages
• Manufacturer brochures — New car specification sheets typically include the insurance group for each variant

4. Cheapest Insurance Groups for New Drivers

If you are a new or young driver, choosing a car in groups 1–10 can save you hundreds or even thousands of pounds per year. Here are popular cars in the lowest groups:

5. Most Expensive Insurance Groups and Why

Cars in groups 40–50 are the most expensive to insure. These are typically high-performance, luxury, or exotic vehicles where repair costs are extremely high and theft risk is elevated:

• Groups 40–45: BMW M3, Audi RS3, Mercedes-AMG A45, Tesla Model S
• Groups 45–50: Porsche 911, BMW M5, Audi R8, Range Rover Sport SVR

The common thread is power, speed, and expensive parts. A single bumper repair on a Range Rover can cost more than an entire year's insurance on a Citroen C1.

6. How the Same Model Varies by Engine and Trim

One of the most important things to understand is that insurance groups are assigned to specific variants, not just model names. The same car can span 20 or more groups depending on the engine and specification.

This means that choosing the smaller engine and lower trim can significantly reduce your insurance costs without compromising on the car itself.

7. Insurance Groups for Electric Vehicles

Electric vehicles (EVs) tend to sit in higher insurance groups than you might expect given their price. There are several reasons for this:

• Battery replacement cost — An EV battery can cost £5,000–£15,000+ to replace, making write-offs more likely after even moderate damage
• Specialist repairs — Not all body shops can work on EVs, reducing competition and increasing repair costs
• Higher purchase price — EVs generally cost more than equivalent petrol cars, raising the replacement value
• Performance — Many EVs have instant torque and rapid acceleration, increasing the performance risk factor

8. How to Use Insurance Groups When Choosing a Car

If you are buying a used car and insurance cost is a factor (which for most people it should be), here is a practical approach:

1. Shortlist your top 3–4 cars by type, size, and budget
2. Check the insurance group for each specific variant on Thatcham or a comparison site
3. Get actual insurance quotes for each car before you commit to buying
4. Factor in the total annual cost — a car that is £500 cheaper to buy but £400 more per year to insure is a bad deal over three years

Final Thoughts

Insurance groups are one of the most straightforward ways to predict how much a car will cost to insure. Before you buy any used car, spend two minutes checking the insurance group for that specific variant. It could save you hundreds of pounds every year for as long as you own the car.

For new and young drivers especially, choosing a group 1–10 car over a group 20+ car can be the single biggest thing you do to make car ownership affordable.

Insurance groups are a guide and individual premiums depend on many additional factors including your age, location, driving history, and claims record. Always get a personalised quote before purchasing.

Related reading: Cheapest Car Insurance UK Tips | Insurance for New Drivers