A thief disguised with a Teenage Mutant Ninja Turtle mask has driven off with a motorcycle from a high-end Melbourne car dealership after setting fire to a stolen van.

The man was wearing a "Leonardo" mask when he drove a stolen van to the dealership on Doncaster Road at Doncaster, in Melbourne's north-east, earlier this month.

He broke into the dealership about 1:30am before stealing a new black and red BMW motorcycle which he then left on.

However, before leaving the man rammed the rear gates of the dealership with the stolen van and set fire to the driver's side.

It is believed the man is aged somewhere between his late teens to early 30s.