Drivers of older cars may soon be stung for higher car registration costs because their vehicles lack the safety features of newer cars, such as side airbags and electronic stability control.

The levy would increase the ACC component of a car registration for motorists whose cars did not meet star rating criteria.

It is being considered as part of a review which ACC Minister Dr Nick Smith says could reduce the $336 million cost of crashes by more than 42 per cent.

"We know from research that there would be huge savings to ACC if more people chose five-star safety vehicles," Dr Smith told the Weekend Herald.

"We are exploring whether through the ACC levy on the car registrations there could be a discount for the owners of vehicles with a five-star safety rating."

The present ACC levy on a $246 annual car registration on a petrol vehicle is $168.

Dr Smith emphasised that the review was in its early stages and a decision on whether levies would apply to different vehicles would not reported back to Government until March next year.

He rejected accusations that the levy would be unfair to the drivers of older cars.

"If there's a greater risk associated with it then that's just what goes with it. People are making choices every day as to the risks they choose to take and if they choose to be in an older, less safe car, then is it fair that the rest of the community meets the cost of that risk?"

The average age of cars on this country's roads was 12.3 years compared with 9.7 years in Australia and 6.7 years in the United Kingdom, he said. "That is contributing negatively to the economic and social costs of car accidents."

Dr Smith may himself be stung with the increased registration costs if they go ahead.

He said he drove a 2008 Hyundai Getz. An earlier model of the vehicle received a safety rating of just three stars. However, Dr Smith said he chose the vehicle on its "full electric" features because of his other role as Climate Change Minister.

Dr Smith said drivers should not automatically equate the age of a car with decreased safety.

However, the car buyer's Dog & Lemon Guide editor Clive Matthew-Wilson said that was poppycock because only cars aged five years and younger had the side air bags and electronic stability control necessary for a five-star rating.

Mr Matthew-Wilson said the type of vehicle driven was as much a factor in road trauma as socio-economic factors, including a person's age and education.

"It's not going to change the behaviour of the people most likely to cause accidents and it's simply rewarding rich people and punishing poor people," he said.

"The simplest way to ensure that poor people drive safer cars is to ensure that government departments buy the safest cars in their class.

"That way, in five or 10 years' time, when these same cars are bought by poor people, the poor people will be driving safer vehicles."

He said upgrading seatbelts in older vehicles would help.