A proposal to scrap compulsory roadworthy certificates for cars less than five years old has sparked debate on the impact of the costly vehicle checks on road safety.

The state government is poised to decide whether to scrap compulsory roadworthy tests for the sale of “newer” vehicles. Last year the government announced a plan to overhaul Victoria's roadworthy system, which was billed as a “red tape blitz” that would save $73 million a year.

Under three options floated by VicRoads, which are being considered by the government, cars of a certain age would be exempt from roadworthy inspections.

But the Victorian Automotive Chamber of Commerce, a group with 5000 industry members, is campaigning the government to abandon all plans for reform.

Executive director David Purchase said if the changes were introduced there could be “thousands” of unsafe vehicles on Victoria's roads.

“Without a doubt we are likely to see more accidents, we are likely to see more casualties and possibly even more fatalities. That goes without saying,” he said.

In an open letter to Premier Denis Napthine on Wednesday, Mr Purchase said work to reduce the road toll would come “undone” if roadworthy restrictions were loosened.

“This is not a red tape issue, nor is it about vehicle age or kilometres. It's about safety on Victoria's roads and protecting unsuspecting buyers,” the letter said.

Associate professor Stuart Newstead, of the Monash University Accident Research Centre, said the link between road trauma and unroadworthy vehicles was “not very high”.

Professor Newstead, who has studied the benefits of periodic roadworthy inspections in New Zealand, said it was unlikely there would be an increase in car accidents as a result of the proposed changes.

“It's not to say that there's no benefit at all, but the cost of doing the inspections compared to the benefit that you get from trauma savings is very small,” he said.

Under the base proposal being considered by the government, cars that are less than three years old would not have to undergo a roadworthy inspection. The most extreme proposal is for cars up to five years old being exempt from a safety check.

Two of the three cost-cutting options also include shortening roadworthy tests.

The RACV said it supported scrapping roadworthy tests for cars less than three years old but only if a mileage requirement ruled out those vehicles that had travelled more than 60,000km.

In its submission to VicRoads, RACV also raised concerns about fleet vehicles being exposed to a risk before the three year limit. “If the vehicle is sold before three years, there will be no checks on such items,” it said.

RACV's Brian Negus said a shorter roadworthy test was supported if it focused on tyres, brakes and steering. “These are critical in controlling a vehicle safely,” he said.

VicRoads has received more than 300 submissions to the roadworthy review. A spokesman said regulating roadworthy certificates cost $196 million a year and cited figures showing vehicle defects contributed to 1.2 per cent of fatal car crashes.

A spokeswoman for Transport Minister Terry Mulder said VicRoads had compiled the feedback and government will consider its recommendations.