After competing in karting and Formula BMW, Rast won the 2005 ADAC Volkswagen Polo Cup and was runner-up at the 2006 Seat León Supercopa Germany.
Rast won the 2012 24 Hours of Daytona GT class, driving a Magnus Racing Porsche 911 GT3 Cup with co-drivers Andy Lally, Richard Lietz and team owner John Potter.
Rast debuted at the 2014 24 Hours of Le Mans with a Sébastien Loeb Racing Oreca-Nissan, finishing fourth in the LMP2 class.
In 2016, he raced full-time for G-Drive with an Oreca-Nissan LMP2, claiming a win at Bahrain and a second place at the 24 Hours of Le Mans and two third-place finishes at Silverstone and Austin.
Rast competed in two rounds of the 2016 Deutsche Tourenwagen Masters with an Audi RS5, finishing sixth at Hockenheim II race 1.
[4] Rast debuted in Formula E at the 2016 Berlin ePrix replacing António Félix da Costa (who had a DTM commitment) at Team Aguri.