A graduate engineer, Mark merely dabbled with racing at first but he was good enough to take a class of the SCCA production sports car championship in 1961 in an Elva Courier, then racing a Formula Junior Elva and a TVR before taking a championship double in 1965 with a Lotus 25 in SCCA class C and a Mustang in class B. By this time Donohue had been taken under the wing of Walt Hansgen, who was leading the works Ford Mk II sports car challenge in 1966. The pair shared second place at Sebring that year, Donohue's first major placing, but his mentor was tragically killed at the Le Mans testing in April, and Mark renewed an old association with Roger Penske, taking his Group 7 Lola-Chevrolet to a victory at Mosport in Can-Am before winning the 1967 and 1968 US Road Racing Championships.

    Penske also entered Donohue in the Trans-Am championship in 1968, and Mark won ten of the 15 events to win the title easily, repeating the trick the following year with six wins from 12 starts. The 1969 season also saw Penske's first appearance at the Indy 500 as an entrant, Donohue qualifying fourth and finishing seventh to earn the 'Rookie of the Year' title. He was to finish second in the race in 1970 driving a Lola-Ford, and later on that season raced in Formula A, winning two of the three rounds he entered. Penske expanded his racing activities in 1971 and Mark faced a hectic schedule of Trans-Am (taking his third title), USAC (winning the Pocono 500 and the Michigan 200 in a McLaren) and sports car events, sharing a blue-painted Ferrari 512M with David Hobbs. However, his performance of the year was undoubtedly his Grand Prix debut at Mosport, Donohue taking a superb third place in Penske's McLaren M19A.

    Grand Prix racing was just a diversion at this stage, for in 1972 Mark continued to race in USAC, duly winning the Indianapolis 500 in a Penske McLaren, and returned to Can-Am, where his title chances were ruined by a testing accident which saw him sidelined for a couple of months. He was back in 1975, however, and made no mistake this time round, taking six race victories and the championship in a Porsche 917. Mark announced his retirement at the end of the year, but was tempted back behind the wheel late in 1974 to apply his superb development expertise to the Penske Grand Prix challenger.

    He was persuaded to race the car in 1975, but it was a disappointment to all concerned and Penske replaced it in mid-season with an 'off-the-shelf March. Donohue was practising the car for the Austrian GP when a tyre is thought to have deflated, sending the March into catch fencing and over the Armco barrier. One marshal was killed and another seriously injured, but at first Mark, though dazed, was sitting up and talking. He seemed to have escaped relatively unharmed, but it was soon apparent that all was not well as he lapsed into unconsciousness and, despite brain surgery, he died three days later in Graz hospital.

(c) 'Who is Who' by Steve Small, 2000