Unable to find a seat in Formula One, Kox moved to touring cars driving a BMW, winning five races in the Dutch series in 1993 on his way to the championship title.

In 1996 he joined BMW Motorsport, making a handful of British Touring Car Championship appearances but focusing his efforts on the development program for the McLaren F1 GTR, winning a race in the BPR Global GT Series.

The following year he joined the Carly Motors squad in a BMW and also took a win in a one-off race in the FIA GT Championship, with the Prodrive Ferrari 550 Maranello.

Kox continued with Prodrive for the following seasons, winning the GTS class in the Laguna Seca ALMS race in 2002 and the 2003 24 Hours of Le Mans.

Peter Kox was a development driver for the Acura NSX GT3 in 2016, and will drive it in the 2017 Pirelli World Challenge for RealTime Racing.