The coding system is used by the industry as a gauge for calculating motorists' premiums. But a rise in the number of new cars on offer - up 42 per cent to 6,000 models in the past three years - has prompted the shake-up.
Ever-changing repair techniques, an increase in the number of spare parts such as air-conditioning units, plus vehicle weight, are also to blame, according to the Association of British Insurers. It says the number of groups will expand from 20 to 50 later this year.