Police are investigating a collision in St Albans earlier this month, which has now turned fatal.
Emergency services responded after a vehicle travelling along Main Road East struck the side of a mobility scooter.
The impact caused the scooter rider to fall out onto the road, injuring his hip.
The 85-year-old was taken to hospital with non-life-threatening injuries but has since died.
The 44-year-old South Yarra woman driving the car is assisting police with enquiries.
Anyone who witnessed the crash or with dashcam footage is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au.