A Melbourne woman was left fearing for her life after a car stacker fell more than a metre while she was parking her car.

Sandra and Justin Shmith of South Yarra spent about $45,000 buying the stacker, which allows more cars to be parked, typically by raising or lowering one vehicle so other vehicles may be parked above or below it.

The stricken Range Rover in the Shmith's garage.

Their three-vehicle stacker was installed in their garage in June and Mrs Shmith was the first person to use it.

"I was in a stationary position and I was only in there for a matter of seconds and then the whole thing just gave way and dropped ... like if a lift had dropped to the bottom," she said.