Mark Donohue Jr. trademark was his versatility. He raced and won in sports cars, Indy Cars, stock cars; on both oval tracks and road courses. He was a two-time USRRC Champion, a three-time SCCA Trans-Am Champion, a Can-Am Champion, winner of the 24 Hours of Daytona, the Indianapolis 500 and a NASCAR Winston Cup race at Riverside, Calif.

Donohue began racing at the age of 22 in a 1957 Corvette. He began to make a name for himself racing sports cars becoming Class champion in the SCCA sportscar championship of 1961. In 1965 he was a double Class champion an in 1966 he was signed by Roger Penske on a race-by-race basis for the USRRC and Can-Am series. The Penske partnership developed into a strong bond between the two men not unlike the bond between Clark and Chapman or Stewart and Tyrrell. Donohue driving a Lola-Chevrolet, won three Can-Am races that year and finished second in the final standings. In 1967, he swept six of eight races to win the USRRC crown and repeated as its champion a year later. That same year, he also drove a Camaro to 10 wins in 13 races to take the Trans-Am crown.

Mark Donohue went to the Indianapolis 500 for the first time in 1969 and was named rookie of the Year with a fourth-place finish. In 1971, he became the first man to top 180mph in qualifying at Indy with a speed of 185.004 mph, but mechanical problems put him out of the race. He returned to Indy in 1972 and won with an average speed of 163.465 mph.

In 11024, the Penske team switched to the AMC Javelin and by 1971, Donohue dominated the competition to capture the championship. In 1973, Donohue drove an American Motors Matador with which he won the season-opening 500-miller on the road course at Riverside, Calif. giving American Motors its first NASCAR win.

1973 was the high-point of Donohue's racing career when he became Can-Am champion driving the awesome Sunoco Porsche 917/30 to 6 wins. This twin-turbocharged unlimited monster is considered by many as the fastest race car ever built.

Coaxed out of retirement by his long-time employer and friend, Roger Penske, he joined his fellow American on the Formula One circuit. They had raced earlier in Formula One, Donohue finished third in the 1971 Canadian Grand Prix, but this was a new car, part of a stronger effort or so it seemed but while practicing for Austrian GP, a tire thought to have deflated, pitched his car into the catch fencing and over barrier, killing a marshal, injuring another. His helmet struck one of the fence post and he was momentarily knocked unconscious but otherwise apparently unharmed, he continued to complain of headaches and later lapsed into unconsciousness, dying two days later in a Graz hospital, despite brain surgery.