Two appliances attended the fire.
A man left a welding unit unattended and City Station Officer Steve Clarke said it was the likely cause of the fire.
''A young man was working on his car ... and walked away for five minutes and came back to check and it was on fire,'' Mr Clarke said.
No-one was injured.
Firefighters took about five minutes to extinguish the fire.
The garage in which the car was parked was also damaged.