An H&A Print car parked at Majestic Square was tipped over on Wednesday night by a group of "young lads", owner Ed Boyd says.
It is the fourth time in six weeks one of Mr Boyd's cars have been tipped.
Footage from CCTV cameras showed the group pushing the car over, though Mr Boyd was unsure of how many were involved.
He said the car was being used for advertising. He was called about 9.30pm on Wednesday, but the car had been picked up by the time he arrived.
There was some damage to the right side of the vehicle.
"Young lads tipped it over and took off," he said.
"It's just sad that young ones seem to think that that's what they're supposed to do."
Two other times when it happened, Mr Boyd's neighbour, panelbeater Ian Chamberlain, repaired the damage for free.
"For me it's just a sad thing. We're trying to make Whanganui a wonderful place to live, all positive, and these sort of negative things happen.
"It's just one of those things, I'm not going to get all wound up over it, that doesn't help you at all."