Stuppacher came from Vienna, Austria. He competed in hill-climbs and sports car races with his Porsche 906 in 1969 and with the Bosch Racing Team Porsche 910, teaming up with Niki Lauda at the ICM Austrian Grand Prix. He carried on, winning the Austrian Mountain Championship in 1971 having purchased a Porsche 908 spyder from Lauda, and endurance racing.
In 1976 he entered four Formula One Grands Prix with the ÖASC Racing Team. The ÖASC Racing Team was an Austrian outfit that had managed to aquire an ageing Tyrrell 007, a Cosworth V8 engine and some Goodyear tyres for a reported £20,000.
The plan was to enter both Stuppacher and fellow Austrian, Karl Oppitzhauser in a March 761, in the Austrian GP. Unfortunately his entry was refused. Otto took a petition around the other teams to try to get support but as an unknown, he failed.
At the 1976 Italian Grand Prix he failed to qualify by a considerable margin. He was over 13 seconds slower that Jacques Laffite on pole. However he was promoted up the order when three other cars had their times disallowed due to fuel irregularities. Unfortunately, Stuppacher had already left the circuit and returned home, and was unable to get back to the circuit in time to race. The three demoted runners, Mass, Watson and Champion to be James Hunt, were eventually re-admitted after the withdrawal of Stuppacher and Arturo Merzario.
Stuppacher failed to qualify at his other two attempts in 1976, the Canadian Grand Prix and the USA East Grand Prix, the latter seeing him over 27 seconds off the time of the pole-sitter.
It is not clear how much racing Stuppacher did after 1976, and very little is known of him until he was found dead in his flat in Vienna in 2001.