Firefighters were called to the blaze at Fusco Vehicle Sales in the Balloo Industrial Estate in Bangor on Friday afternoon.
At the height of the blaze, a series of fire crews were at the scene.
The operation continued through the night, and crews finally left the area shortly after 9am today.
The fire is thought to have started accidentally, the NI Fire & Rescue Service said.
Local DUP MLA Stephen Dunne praised the emergency services for ensuring the fire’s impact was not more severe.
The scene at Fusco Vehicle Sales in Balloo Industrial Estate in Bangor, where a fire on Friday evening destroyed the dealership workshop. Jonathan Porter/PressEye
In an update, the NIFRS said: “Following assessment early this morning firefighters have now left scene as of 9.20am.
“At the height of the incident six appliances, one aerial ladder appliance, one command support unit, one water tanker and three officers were in attendance. Firefighters utilised breathing apparatus, firefighting jets, aerial jets and unmanned ground monitors to extinguish the fire.
“We would like to thank the public and impacted business for their co-operation.
“The cause is believed to be accidental.”
In a post on social media, Fusco Vehicle Sales said: “Firstly we would like to take a moment to wholeheartedly thank the Northern Ireland Fire & Rescue Service who were with us throughout the night keeping the rest of our site and neighbours safe.
“We are absolutely amazed this morning at how much of our stock and site was kept away from the fire through their work.”
Fire crews tackling an ongoing Bangor fire at Balloo Road industrial estate. Pacemaker
News Catch Up – Friday 9 January
At the height of the blaze, the PSNI issued safety advice for those travelling or living in the area, urging those nearby to keep their windows closed.
Large plumes of smoke could be seen over Bangor as the fire raged.
Fire crews tackling an ongoing Bangor fire at Balloo Road industrial estate. Pacemaker
Mr Dunne, an MLA for North Down, said he was relieved that everyone is safe.
“My thoughts are with the staff and management at Fusco Group at what will undoubtedly be a worrying time,” he said. “The Fusco group are significant local employers and have been for many years within the Bangor area.
“I want to place on record my sincere thanks to the Northern Ireland Fire & Rescue Service and the PSNI for their swift, professional and coordinated response, which ensured the situation was brought under control quickly and safely.
“There are a lot of local businesses within the Balloo area and many homes also in close proximity to the fire.
“This fire had the potential to have devastating consequences so we can be very thankful that it was able to be brought under control thanks to the swift response of our emergency services.”
North Down MP Alex Easton paid tribute to emergency personnel as they responded to the fire.
The scene at Fusco Vehicle Sales in Balloo Industrial Estate in Bangor, where a fire on Friday evening destroyed the dealership workshop. Jonathan Porter/PressEye
Mr Easton added: “My thoughts are with everyone involved, including those working to bring this incident under control.”
Meanwhile, Alliance MLA Connie Egan said: “I am extremely grateful to the Fire and Rescue Service for their prompt and professional response to the fire, which could have caused even more damage had they not managed to bring it under control quickly.
“This was a very major fire and has obviously caused quite a lot of concern to those living nearby.
“My thoughts are with the team at Fusco, who will be incredibly distressed. I just hope that no one has been injured as a result.”