Road safety authorities say extending probationary licences by an extra three years could cut the road toll.

Victoria Police Assistant Commissioner Robert Hill says 40 per cent of 20 to 25-year-olds killed or injured on the road each year had been drink driving.

He is calling for discussion on a graduated license system until drivers turn 25.

Bruce Corban, from Monash University's Accident Research Centre, says extending probationary periods would save lives.

"I would imagine that we'd be looking for something in the order of 30 to 40 fewer deaths each year and probably ten to 20 serious injuries," he said.

Assistant Commissioner Hill says it is time for a public debate.

"It is very very sad to see young people in the prime of their lives losing their lives in circumstances that could have been avoided," he said.

"They're more inclined to make rash decisions. Decisions not understanding the consequences of those impulsive behaviours."

Premier Denis Napthine says it is important to be realistic when considering the issue.

He says there will be no decision until the state's road safety committee looks into the matter further.

"It involves the police and the TAC. We're open to all suggestions that will improve road safety," he said.

"They need to be tested and if they are efficatious then we will implement them."

But the head of Victoria's peak motoring group does not support the changes.

Brian Negas from the RACV says current research does not support a change in law.

"I think the evidence needs to be there to ensure you are going to get the same levels of reduction," he said.

"You're not going to impose additional legalistic requirements on the community. There needs to be a balance between the law and community values."