An Aixam GT Crossline was left teetering over rocks at Albert Promenade, Halifax, after a three-point turn went drastically wrong.
The 84-year-old driver was with his wife, 82, when the car shot back and smashed through a wall.
Both escaped injury but were left shaken and shocked on top of rocks just yards from a huge drop.
PC Jan Walker said the driver was attempting a three-point turn in his automatic car.
“He had thought it had come out of reverse but it hadn’t and shot back,” she said.
“It’s hair-raising when you think what could have happened.”
Halifax man Zahir Khan, 37, was sat nearby when the accident happened on Tuesday afternoon.
“The car was reversing and the driver lost control but luckily the car stopped,” he said.
“He got out and I helped the lady out - she was shook up.”
Mr Khan said he wanted the couple out of the car quickly in case it rolled back.
A recovery truck was called out to remove the car.