A pedestrian is still fighting for his life in hospital while police wait to speak to an elderly driver whose car ploughed into three people, killing a woman.

The tragedy could trigger changes to Victoria’s licensing rules for older drivers, as one expert warns senior motorists are a critical cohort to target with safety measures.

The trio were walking on a footpath in suburban Wantirna South, in Melbourne’s east, when a 91-year-old driver lost control of her car.

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The Toyota Yaris mounted a footpath before hurtling down a hill and smashing through a fence and into a bench on Thursday.

The woman, 59, died at the scene while the man, 60, remains in a critical condition.

The two-year-old boy was seriously injured but his condition had been stabilised in hospital on Friday.

Investigators, yet to interview the elderly driver, will assess whether speed was a contributing factor.

The incident has prompted the state government to consider previous calls for older people to prove they are fit to drive, in line with rules in other states.

Victoria does not have age-based driving safety requirements, although drivers aged 75 and older must renew their licence every three years, which can involve various tests.

NSW, Queensland, the ACT, Tasmania and the Northern Territory require drivers older than 75 to have a health check, while older drivers in South Australia must complete self-assessments.

In Western Australia, an annual medical assessment is required to renew a driver’s licence from the age of 80.

There were two critical times in a driver’s road safety journey, Australian Road Safety Foundation chair Russell White said.

They were the first five years after obtaining their P-plates and from the age of 55 onwards.

“Where it might be inexperience and a bit of bravado at the younger-driver end, the delayed reaction, poor vision, health issues and cognitive ability all decline as we get older,” White told AAP.

But individual drivers had varied abilities as they aged, so a staged approach was needed.

Australasian College of Road Safety chief executive Ingrid Johnston has called for a study to compare the outcomes of various jurisdictional models to determine the best approach to roll out nationally.

She said authorities also needed to support older drivers with opportunities to maintain safe driving and provide alternatives when that might no longer be possible.

The crash happened during the first week of Victorian school holidays, bringing the state’s road toll to 14 in seven days.