The blaze hit the Moray Motors yard at Coulardbank Industrial Estate, badly damaging four vehicles – two of which were owned by customers.
Personnel manning the main gate at nearby RAF Lossiemouth raised the alarm with two fire appliances quickly on the scene – one from the local station at Lossiemouth and a second from Elgin.
A spokesman for the Scottish Fire and Rescue Service said: “Four firefighters with breathing apparatus attended the call at 2.30am and left the scene at 3.05am.”
Investigating the incident is Detective Constable Gary McTurk, who said: “This is a very unusual incident and I am keen to speak to anyone who may have been in the area at the time.”
Police say they are particularly interested in tracing a person dressed in light-coloured clothing who was seen walking away from the premises at around 2.30am.
Owner of the garage, Keith Attwood, said that he hoped their would be no long-term impact on his business, adding: “We’ve arranged for one of the cars that’s been abandoned in the middle of the forecourt to be uplifted.
“Hopefully we can get the place looking a bit tidier and we are just waiting for the insurance assessor to come down and see about the rest. I want to reassure customers that their cars are safe.”
Police say that anyone with information should contact them on 101 or through the Crimestoppers confidential line on 0800 555111.