Car Insurance Groups

Cars in lower insurance groups attract a lower premium, so it's worth understanding how insurance groups work.
Members of the Association of British Insurers (ABI) and Lloyds Market Association (LMA) are the people who set the car insurance groups. Research is carried out on all new passenger cars and results are passed on to the panel, who then decide into which insurance group the car should fall. There are 20 groups of car insurance and the car with the higher performance are those which are likely cost the owner the most in insurance.
The Motor Insurance Repair Research Centre - Thatcham, who conduct research on new cars have created more insurance groups as they believe cars can be more accurately branded.
Insurers make up their own mind whether to use 20 or 50 groups or as these groups are reccomendations only they may use their own group ratings.

New car insuranced groups are assessed on the following points:

The cost of repair and parts which are the most likely to be damaged on a car.
It is believed that vehicle repairs accounts for over half of all money paid out on motor insurance claims so this factor plays a large part in defining the insurance groups.
The cars value.
Replacement and repair is determined by how much the new car costs.
The standard security fitted to the car.
The better the standard security a new car has the more it can keep down insurance claim costs. Immobilisation systems, lock, alarms, VIN numbers, glass etching, alloy wheel locks etc are all ways to improve a cars security.
A new car's performance.
It is a fact that the higher performance cars are the more likely to crop up in insurance claims, therefore top speed and acceleration play a big part in insurance group classification.