Kumpen currently works as driver and team manager for PK Carsport in the NASCAR Whelen Euro Series.

[6] In 2014, he competed in the NASCAR Whelen Euro Series for the PK Carsport team, driving a Holden VF Commodore.

He won one race in the championship, and ended the season in first place, one point ahead of defending champion Ander Vilariño.

[10] He continued his part-time slate in the Xfinity Series in 2017, adding two races at Daytona and Mid-Ohio Sports Car Course, driving the No.

[11] Kumpen was also in discussions with Rick Ware Racing to make his Monster Energy NASCAR Cup Series debut with the team in 2018,[12] but it never materialised because of his doping suspension (NASCAR is a member of ACCUS, which honours FIA doping suspensions such as the one imposed by the Royal Automobile Club of Belgium).

Kumpen was suspended for four years by the Royal Automobile Club of Belgium after he failed a drug test during the 2018 24 Hours of Zolder.

[21] In 2010, Kumpen participated in Sterren op de Dansvloer (the Belgian version of Dancing with the Stars) on vtm.