Car insurance groups explained

What insurance group is my car, and what do insurance group numbers mean?

TL;DR: What are the UK car insurance groups?

Car insurance groups determine how much it costs to insure any car on UK roads — and understanding them before you choose your next lease deal could save you a significant amount on your annual premium.

Every car sits somewhere on a scale from 1 to 50, with the number determined by Thatcham Research based on factors like value, repair costs, performance, and security.

The system is also changing, with a new Vehicle Risk Rating model replacing the 1–50 scale for newer cars.

What are car insurance groups, what affects them, and are electric cars cheaper to insure?

Understanding car insurance groups before you choose your next lease deal could save you a significant amount on your annual premium.

Every car on UK roads sits somewhere on a scale from 1 to 50.

Group 1 cars are the cheapest to insure. Group 50 cars are the most expensive.

The number is worked out by Thatcham Research, who weigh up everything from a car's value and repair costs to its performance and security features.

Here's what the system means, how it works, and how to use it to your advantage.

What are car insurance groups?

Car insurance groups categorise every car on UK roads by the risk it poses to insurers — and how much it's likely to cost them if something goes wrong.

The system is currently in transition, so here's how both versions work.

The current system: Groups 1-50

Every car sits somewhere on a scale from 1 to 50.

The number is assigned by Thatcham Research, who assess around 125 factors (from a car's value and repair costs to its performance and security features) to determine where each new model lands.

Group 1 is the cheapest to insure; group 50 is the most expensive.

The new system: Vehicle Risk Rating (VRR) model

For cars that have gone on sale from August 2024 onwards, Thatcham is transitioning to a new Vehicle Risk Rating (VRR) model.

Rather than a single number, each car receives five separate scores (covering performance, damageability, repairability, safety, and security) each rated from 1 (low risk) to 99 (high risk).

What factors affect your car insurance group?

The group your car lands in isn't arbitrary — it's the result of a detailed assessment process. And as the system evolves, so does what gets measured.

The current system: Groups 1–50

Thatcham Research assesses around 125 factors in total, but the main ones that determine where a car sits on the scale are:

• Value: A more expensive car costs more to replace, which insurers factor in from the start
• Repair costs and time: Modern cars are complex to fix — specialist parts and labour don't come cheap, and how long a repair takes matters as much as the cost
• Performance: Higher acceleration and top speed statistically correlate with a greater likelihood of a collision
• Safety features: Technology like Autonomous Emergency Braking (AEB) can actively reduce the risk of an accident, which insurers reward with a lower group
• Security: Alarms, immobilisers, and other anti-theft measures reduce the likelihood of a claim, which can bring a car's group down

The new system: Vehicle Risk Rating (VRR)

The VRR model assesses the same broad areas but in greater detail — and adds two new assessment categories that the 1–50 system didn't explicitly cover:

• Damageability: How a car's design, materials, and construction affect the severity and cost of repairs
• Repairability: Whether a transparent, cost-effective repair strategy exists for the vehicle, including parts availability and ease of access

The shift reflects how much cars have changed.

EVs, software-defined systems, and advanced driver assistance technology all introduce risks the original 125-factor model wasn't built to capture.

What other factors affect your car insurance cost?

Your car's insurance group is just one piece of the puzzle.

When calculating your premium, insurers also weigh up a range of personal factors — most of which have nothing to do with the car itself.

• Your age: Younger drivers typically face higher premiums due to limited driving experience
• Where you live: Your postcode gives insurers an indication of local crime rates and traffic patterns
• Your job: Some occupations are considered higher risk than others and can push premiums up
• Your driving history: A clean record with no claims works in your favour. Previous incidents (even ones that weren't your fault) can increase what you pay
• Your policy type: Fully comprehensive cover can actually cost less than third-party only. This works in your favour when leasing, because most funders require fully comp as standard

What do the letters mean in car insurance groups?

Your car's insurance group number sometimes comes with a letter attached, like 12D or 25E.

Not every car has one though; where no letter appears, the car meets the standard security requirement for its type.

Where a letter is present, it tells you a few things:

• A: Security meets the standard for the type of car
• D: Security falls below the standard — the car has been moved up a group as a result
• E: Security exceeds the standard — the car has been moved down a group as a result
• P: Provisional — not enough data was available at the time of launch to give a full rating
• U: Security is at an unacceptable level. An insurer may require an upgrade before agreeing to provide cover
• G: The car is a grey import and hasn't been assessed for the UK market

Are electric cars cheaper to insure?

Despite being cheaper to run day-to-day, electric cars are typically more expensive to insure than their petrol equivalents — though the gap varies more than you might expect.

Research from The Electric Car Scheme puts the difference at anywhere between 15 and 25%.

This is driven by a combination of faster acceleration (which insurers associate with higher accident risk) and the cost of repairing or replacing a battery pack, which can account for up to 40% of a car's total value.

That said, it isn't a universal rule.

A Vauxhall Corsa Electric, for example, is actually slightly cheaper to insure than the equivalent petrol model. Meanwhile a BMW i4 can cost significantly more to cover than a comparable petrol BMW.

The insurance group of the specific car (and the trim level) still does a lot of the work.

The good news is that this is an area the industry is actively working to improve. Thatcham Research has developed a framework of recommendations aimed at making EVs cheaper and easier to repair.

If adopted by manufacturers, this should help bring insurance costs down over time.

Can you reduce your car insurance cost?

Your insurance group sets the baseline for insurers, but there's plenty you can do to bring the actual cost down:

• Pay annually: Paying monthly is essentially a loan, and the interest adds up. A single annual payment is almost always cheaper overall
• Increase your excess: Agreeing to pay more in the event of a claim signals to insurers that you'll only claim when you really need to — which can reduce your premium. Just make sure the excess stays affordable if you do need to claim
• Build your no-claims bonus: Every claim-free year works in your favour. Where possible, avoid making small claims that could cost you more in lost discount than they're worth
• Upgrade your security: Approved alarms, immobilisers, or secure off-street parking can all help bring your premium down
• Consider telematics insurance: A black box policy lets you demonstrate your driving to an insurer with real data rather than assumptions. If you're a careful driver, it can make a meaningful difference to what you pay

The future of car insurance groups

The 1–50 system is being replaced — though for most cars on the road today, it still applies.

Thatcham Research is transitioning to a new Vehicle Risk Rating (VRR) model, which assesses each new car across five areas:

• Performance
• Damageability
• Repairability
• Safety
• Security

Each is scored from 1 (low risk) to 99 (high risk).

The five scores are aggregated into an overall insurance risk rating, giving insurers a far more detailed picture of a vehicle than a single group number allows.

The change is being driven by the growing complexity of modern cars — from EV structures and repair challenges to software-defined systems and cybersecurity risks — which the existing 125-factor model wasn't designed to capture.

Until VRR becomes the industry standard, the 1–50 group system remains.

The bottom line

Car insurance groups aren't the most glamorous part of choosing a lease, but they're one of the most practical. Knowing where a car sits on the scale before you sign can make a real difference to what you pay each year.

The cheapest car to lease isn't always the cheapest to run.

Factor in the insurance group alongside your monthly payments and you'll get a much clearer picture of the true cost.

Browsing lease deals? You'll find the insurance group listed in the vehicle details on every car at Carparison. This means that you can compare before you commit.