While testing a car motor in one of the buildings at an automaker’s R&D centre around 7:45 am, a technician noticed the presence of a diffuse white-coloured “fog” on the roller bench. Suspecting that the exhaust sleeve had burnt, he stopped the ongoing test and, upon observing fire igniting under the vehicle, immediately left the premises. At the same time, flame detection activated the alarm notifying in-house fire-fighters and the bench control room technician, who also witnessed the flames. He tripped the emergency shutdown, which automatically closed all utility lines. CO2 extinction started up; with the flames resisting, the water sprinkler system was then triggered. Some personnel of the ignited building and an adjacent building were evacuated. A few minutes later, with the fire apparently extinguished, the sprinkler network was turned off and the test room’s smoke extraction system switched on. A new fire outbreak was detected around 8:30 am, at which point the extinction network was reactivated and public responders called. Out of precaution, all personnel from 3 buildings were evacuated. Fire-fighters brought the blaze under control by 9 am using a foam nozzle; clutter was removed from the scene. First responders remained on-site until noon. A specialist subcontractor treated the 6.5 tonnes of extinction water collected in the test bench pit; another 3 tonnes of liquid waste resulting from cleaning 5 of the site’s hydrocarbon separator-decanters were also removed by a subcontractor. The vehicle was destroyed and the test bench damaged; the tests scheduled on this bench were cancelled, postponed or transferred. According to the facility operator and insurance adjuster, a leak of exhaust gases or oil in the vicinity of the car’s turbo device could have caused this accident. The CO2-based extinction was undoubtedly insufficient, given the lack of a diffuser nozzle for the motor temperature (which could not be adequately cooled); moreover, keeping the motor on after the outbreak only promoted the spread of the fire. The operator issued a reminder of test conditions for roller benches and proceeded to: determine the resources needed to tie the vehicle shutdown (cut-off of both energy and fuel) with fire detection or extinction; re-evaluate risks in order to account for changes in test conditions and certain vehicle configurations; post a description of the items tested and their respective level of hazard (fuels, hybrid batteries, air conditioning gases, etc.) on the control console.