Twelve fire engines and around 80 firefighters tackled a fire at an industrial unit on Sandiford Road in Sutton.
A single-storey car workshop was destroyed by fire and around 20 vehicles were damaged. There were no reports of any injuries.
The Brigade was called at 2339 and the fire was under control by 0240. Crews from Sutton, Wimbledon, New Malden and surrounding fire stations attended the scene.
The cause of the fire is under investigation.