Taggarts Land Rover in Motherwell has suffered approximately £850,000 of damage following an arson attack.
A Scottish Fire and Rescue Service spokeswoman said the fire involved eight vehicles and a further 10 were affected by radiated heat.
She said: “A fire investigation team went out and left the incident at 3.44am on Thursday."
Police Scotland said a man was caught on CCTV climbing the perimeter fence on Wednesday night and starting a fire in the forecourt.
The fire was found to be deliberate after a joint investigation between police and fire services.
Det Insp Kenny Dalrymple, from Wishaw CID, said: "Extensive inquiries are under way to establish the full circumstances surrounding this reckless crime and it is absolutely vital that anyone with information comes forward.
"We know that the suspect climbed the fence to start the fire and I would appeal to anyone who was in the vicinity of the garage around the time of the incident and may have noticed someone acting suspiciously to get in touch.
"I would particularly appeal to any motorists with dashcams who were driving along Windmillhill Street between 23:30 and 23:50 to contact police as you may have captured footage which could be important to our investigation."
Anyone with information is asked to contact Wishaw CID via 101, quoting incident number 4577 of Wednesday 20 June 2018.
AM100 dealer group Lookers, which trades as Taggarts in Scotland, said in a statement: “We have been informed of the fire at Taggarts Land Rover Motherwell. We will now follow our protocols and processes and consult with the appropriate authorities to assist with their investigation into this incident.
"We remain open to the public and will provide an update within the next 48 hours. We apologise to our customers for any inconvenience caused.”