Adam began his racing career in sports cars towards the end of the 1970s, initially competing as a privateer and earning a Canadian championship before becoming a professional driver. In 1980, he joined the factory-backed Group 44 race team, co-driving with Bob Tullius in the Triumph TR8 in the IMSA series. He achieved GTO class victories at the 12 Hours of Sebring, Road Atlanta, Mosport, and Road America with the team.
Adam drove alone to victory at Daytona. In mid-1982, Group 44 unveiled its Prototype Jaguar GTP racer, finishing third in its debut race at Road America. The 1983 season saw Adam and Tullius lead numerous races, securing wins at Road Atlanta, Lime Rock, Mosport, and Pocono, despite the car’s fragility.
Adam moved to Conte Racing in 1985, partnering with John Paul Jr. in the factory-backed March GTP racer. This car was powered by a Buick V-6 turbo engine producing over 1000HP, but proved unreliable despite its performance potential. Subsequent years were spent with Bayside Racing in their Porsche 962 GTP racer and Hendricks Motorsport in a Chevrolet Corvette GTP racer. He also competed in the Rothmans Porsche Cup in Canada in 1986 and 1987, achieving numerous victories and receiving a prestigious Porsche Cup award.
At the 1987 24 Hours of Le Mans, Adam drove a Porsche 962C for Porsche Canada/Brun Motorsport alongside Scott Goodyear and Richard Spenard, reaching fifth overall before retiring with engine problems. He later drove for Protofab, racing factory-backed Camaro and Corvette race cars, before a period away from motorsport.
Adam returned to racing in 1994 with Champion Racing Porsche, achieving a second-place finish at the Sebring 12 Hour in 1995 with Hans-Joachim Stuck, alongside co-drivers including John Paul Jr., Juan Manuel Fangio II, Brian Redman, and Thierry Boutsen. He and Stuck then won the 12 Hour Sebring GT1 class in 1996. In 1997, Adam placed second in class at the 24 Hours of Daytona with Stuck and Boutsen.
In 2002, Adam participated in two races of the Porsche Supercup at the Indianapolis Motor Speedway, finishing 11th and 13th. The following year, he drove the number 23 Porsche 911 twice in the Grand-Am Motorola Cup, qualifying second on the grid at Mont Tremblant. More recently, Adam has raced an Audi R8 (chassis 405) in the Historic Sports car Racing series, winning the Daytona WSC Enduro race in November 2005. He won the overall HSR Championship in 2008 driving for Jim Rogers. In 2010, driving for Rogers in a previously unraced Audi R8 (chassis 607), Adam and Butch Leitzinger won the opening HSR race at Sebring. Teaming with Andy Wallace, they secured further victories at Road America and Homestead Miami Speedway, along with pole positions and a win at Road Atlanta, ultimately winning the HSR Championship.
Bill Adam is the father of auto racing reporter Shea Adam.