Vanthoor began his motorsport career in 2002 in karting, where he was active until 2007. Among other things, he won the 2005 French and Belgian Junior Championship title. 2008, the young gun moved to the German Formula 3 Cup, the Dutch team Van Amersfoort Racing. With two wins and a further seven podium finishes, he finished at the end of the season fourth overall. He also finished sixth at the prestigious Macau Grand Prix, in which he also became the youngest participant in the history of this race. 2009 remained Vanthoor at Van Amersfoort Racing and denied his second season in the German Formula 3 Cup. With eleven victories, he won the championship title dominant over his teammate Stef Dusseldorp. Vanthoor was the first driver in 18 years to win the German Formula 3 title with a Volkswagen engine. The last time this was the Dane Tom Kristensen succeeded.
2010 started Vanthoor for the French team Signature in the Formula 3 Euro Series. At the end of the season, he finished with three second places as the best results in sixth place overall. 2011 remained Vanthoor at Signature and denied his second season in the Formula 3 Euro Series. With two second places as the best placements Vanthoor was the second best Volkswagen driver sixth in the drivers' standings. In addition, he was entitled to points in the FIA Formula 3 Trophy 2011. With a third place as best result he reached the fifth place there. After the season Vanthoor participated in DTM test for Audi.
- 2002-2007: Karting
- 2008: German Formula 3 (4th place )
- 2009: German Formula 3 (Master)
- 2010: Formula 3 Euro Series ( 6th place)
- 2011: Formula 3 Euro Series ( 6th place)
- 2011: FIA Formula 3 Trophy ( 5th place)