Peter Ludlow, 56, had expected to pick up his Boxster S from the garage but instead received a grovelling phone call to say his car had been destroyed in a crash.
The former fireman has since accepted £12,000 from the garage's insurers for the eight-year-old sports car which he believes was worth roughly £26,000.
Peter, who bought his Porsche for £46,000 when it had 110,000 miles on the clock five years ago, said: "That Porsche meant everything to me.
" After my divorce and having been estranged from my children it was all I had left."
"I gave it to them at eight in the morning and they were going to give it a full service and drive to the MOT station," he continued.
"They split it up the middle, it's dead."
Peter claims that the engineers at the garage in Marden, Kent, gave his car to the owner's 18-year-old son who drove it at 65mph into the path of a Ford Fiesta on July 25.
He said: "Why the hell would they give it to an 18-year-old who had only been driving for six months?
"He's the son of the owner and he has admitted to driving it down this dangerous road at 65mph," Peter continued.
"The car was a part of me, every part on it was a Porsche part and it was in tip top condition.
"It was all I had and I'm devastated. I am now without a car and whatever I buy next it won't be a Porsche driving experience."
The former fire commander , from Maidstone, Kent, said that during his 33-years' service he had pulled dozens of bodies from car wrecks on the stretch of road where his Porsche was destroyed.
After the crash, where the Porsche smashed into a Ford Fiesta and careered into a 4x4, Project Nine Engineering, who crashed the car bought it for parts.
Kent police are still investigating the smash, but have not made any arrests.
A spokesperson said: "Officers are currently awaiting information, which has been requested from