Neerpasch began racing in the early 1960s, initially in Borgward touring cars. He made his first appearance at the 24 Hours of Le Mans in 1964, which served as an early landmark in his on-track career. His most celebrated result as a driver came in 1968, when he won the 24 Hours of Daytona driving a Porsche 907. Later that same year he recorded a third-place finish at Le Mans, rounding out a period of consistent results at the sport's most demanding endurance events. After that Le Mans result, Neerpasch retired from racing to pursue a career in team management.
In the 1970s Neerpasch moved into management roles in the Deutsche Rennsport Meisterschaft (DRM) and the European Touring Car Championship (ETCC). He first managed Ford's competition effort before moving to BMW, bringing with him 1972 DRM champion Hans-Joachim Stuck. At BMW, Neerpasch founded the BMW M team and was the driving force behind establishing the BMW M GmbH company, which became the performance and motorsport arm of the manufacturer.
One of his most significant technical contributions was leading the development of the mid-engined BMW M1. Designed to take on Porsche in Group 5 racing, the M1 required the construction of 400 road cars for homologation purposes. Recognising that the car needed competitive track miles while those homologation units were being assembled, Neerpasch approached Max Mosley of March Engineering — then a member of the Formula One Constructors' Association — with a proposal for a one-make racing series. The result was the BMW M1 Procar Championship, which ran in 1979 and 1980 as a support series to Formula One Grands Prix. The Procar series gave the M1 high-profile exposure and attracted Formula One drivers including Niki Lauda and Nelson Piquet, elevating the car's reputation substantially. Neerpasch later raced himself in a 2008 one-time revival of the Procar Championship, driving an M1 Procar that had been painted by Andy Warhol.
In the 1980s Neerpasch took charge of the Sauber-Mercedes sports car racing programme. The team competed at the highest level of endurance racing, and Neerpasch guided it to victory at the 24 Hours of Le Mans in 1989. Beyond the team's outright results, his tenure is particularly remembered for his role in identifying and nurturing young driving talent. Among the drivers Neerpasch discovered and developed were Michael Schumacher, Karl Wendlinger, and Heinz-Harald Frentzen — all of whom went on to Formula One careers, with Schumacher becoming a seven-time world champion. Neerpasch's eye for talent and his willingness to give young drivers exposure in competitive machinery is regarded as one of his most enduring contributions to the sport.
Neerpasch's career spans the transition from the privateer-dominated sports car racing of the 1960s to the manufacturer-backed, commercially structured competition environment of the 1980s. His founding of the BMW M motorsport programme gave the manufacturer a competition identity that persists to the present day, while the M1 Procar Championship stands as a model of how a manufacturer can generate maximum visibility for a road car through a focused, single-make racing series. As a talent scout, his roster of discoveries at Sauber-Mercedes places him among the most influential figures in the development of late-twentieth-century Formula One careers.