race, Gartner was given the new turbocharged Osella FA1F as the team decided to run a second car at all the remaining races. At the 1984 British Grand Prix, Gartner was allowed to start in 27th position because the Tyrrell Racing team was participating under appeal. However, his race ended when he was unable to avoid a first-lap accident involving Philippe Alliot and Eddie Cheever. After mechanical failures in the next two races, he finished 12th at the Dutch Grand Prix, five laps down on the winner Alain Prost. At the Italian Grand Prix at Monza, Gartner qualified 24th but finished fifth, beating fellow Austrian Gerhard Berger into sixth after Ghinzani and Cheever ran out of fuel. However, Gartner was denied the two points normally awarded to the fifth-place finisher, as Osella had only entered one car at the beginning of the season. Berger in sixth was similarly denied his single point, driving for ATS. Classified 12th at the European Grand Prix although he retired with fuel injection problems, Gartner closed the season with a 16th place classification in Portugal, having run out of fuel. For 1985, he was in contention for a seat at Arrows, but lost out to Berger. He also held talks with Toleman and Osella, but both seats went to drivers with more finance in place. Endurance racing Gartner had finished fourth in the 1985 24 Hours of Le Mans in a Porsche 962C along with teammates David Hobbs and Guy Edwards. In 1985, after his season in Formula One, he joined the Fitzpatrick Porsche Group C endurance racing team, driving a Porsche 956, and also campaigned a Porsche 962 for Bob Akin in the IMSA GT Championship. He won the 1986 12 Hours of Sebring, along with teammates Akin and Hans-Joachim Stuck, finishing on three wheels, and also won an international race at Thruxton with Tiff Needell. Gartner was aiming to join the factory Rothman's Porsche team for 1987. Whilst contesting the 1986 24 Hours of Le Mans for Kremer Racing with teammates Sarel van der Merwe and Kunimitsu Takahashi, Gartner's Porsche 962 suffered a mechanical failure at 2:10 am on the Sunday morning, and turned hard left into the barriers on the Mulsanne Straight at . The car somersaulted down the track, hit a telephone pole, crashed into trees and then caught fire after it came to a rest on top of the barriers