Brock rose to fame in touring car racing, winning the Bathurst 1000, Australia's most prominent domestic motorsport event, a total of nine times through the 1970s and '80s. As the lead driver for the pseudo-factory Holden Dealer Team, in a succession of Holden Toranas and later Commodores the smooth-talking, clean-cut Brock became a household name well beyond motor racing fans, probably the best known Australian racing driver after Jack Brabham.
Brock and the Holden Dealer Team became involved, with full factory approval and assistance, in producing a number of high-performance modifications to the Commodores of the late 1970s and early 1980s.
Brock developed an interest in New Age-style spirituality through practitioner Eric Dowker. Brock began publically supporting, and eventually began to fit to HDT specials, a device called the "Energy Polariser", containing strong permanent magnets, which claimed to improve the performance and handling of vehicles through "aligning the molecules". The overwhelming majority of the Australian motoring community regarded the device as pseudoscience. Brock also recommended that the tyre pressures for his polariser-equipped vehicles at what many regarded as near-dangerously low levels. Holden, fearing the consequences of being associated with the device, cut ties with Brock and set up an alternative racing/modification operation, Holden Special Vehicles.
Brock continued to race in privately-supported teams for some years afterwards, then finally retired (when?).
He now occasionally competes in various enthusiast-level motorsport events such as the Targa Tasmania. In 2002, he has returned to top-level touring car racing as a team manager with the entry of "Team Brock" into the V8 Supercar category. The team's vehicles are actually constructed by Holden Special Vehicles. His smooth on-camera persona and familiarity to older Australians continues to sell products - currently Mobil oils and Bridgestone tyres, and the huge controversy (at the time) of the Polariser is seemingly forgotten.