Steel began his motorsport career in karting in 1988, where he was active until 1995. In 1996 he made his debut in Formula racing in the German Formula König, in which he finished fourth at first. After he had taken part in several races of the German Formula König in 1997, he joined in 1998 at the German long-haul Cup. After a one year break, he drove in 2000 and 2001 in the German VW New Beetle Cup. He also started in 2001 to race in the German Formula Renault.
In 2002, he went in the German Alfa 147 Cup, the first German racing series with diesel engines at the start and won the runner-up title behind Markus Lungstrass. 2003 steel remained for some races in the German Alfa 147 Cup and finished the season 14th overall. He also took part in a race in the European Touring Car Championship ( ETCC ) for Autodelta.
Mid-2004 steel in the German Seat Leon Supercopa and secured with four wins the championship. In 2005, he remained in that league, could not build on the results from the previous year. He remained winless, finishing in 13th place overall. He also completed one race apiece in the Porsche Supercup and in the GT1 class of the FIA GT Championship.
In winter 2005/2006 steel started on race weekend in Shanghai for assisted Willi Weber's German team in the A1 Grand Prix. He did not come to the placements of Timo Scheider and Adrian Sutil, who denied the remainder of the season, zoom. In 2007 and 2008 he started to individual races in the German Mini Challenge and 2007 also took on the ADAC Procar Series in part. In 2008 he was at the 24 -hour race on the Nürburgring 16 in the overall results and third in the SP3T class.
2009 and 2010 took part in none of steel racing series and served as a test driver and instructor for a Rösrather Motorsport Agency. In 2011 he drove a race for the Brixia Horse Power Team in the Eurocup Mégane Trophy and finished the first race at the Nürburgring in 15th place
Steel mother Barbara is with Rolf Schumacher, the father of Michael and Ralf Schumacher, romantically involved. Michael Schumacher and Sebastian Stahl already know from common Kart hours on the kart track in Kerpen- Manheim. Because of its relationship to the two Schumacher brothers, he is referred to by some media representatives as " Schumi 3".
Steel completed an apprenticeship as an office clerk.
In a cameo of the series Among us Sebastian Stahl played itself