at the wheel of a BMW M3 in the middle of the 1992 Bathurst 1000 race in Australia . . .
http://en.wikipedia.org/wiki/Denny_Hulme
"A favourite event of Hulme's was the Bathurst 1000, held at the famous Mount Panorama track in Australia. In the 1992 event he was sharing a Benson & Hedges-sponsored BMW M3 with Paul Morris. After complaining of blurred vision Hulme suffered a massive heart attack at the wheel whilst travelling part the way down the 200-mph Conrod Straight. After veering into the wall on the left side of the track, he managed to bring the car to a relatively controlled stop sliding against the safety railing and concrete wall. When marshals reached the scene they found Hulme still strapped in, dead."
Jim Cook died of a heart attack at Sears Point during practice in an IMSA race in a March Porsche . . .
http://alex62.typepad.com/imsablog/2007/05/the_march_saga_.html
"A string of consistent results rewarded the team, but it was obvious that they did not have the means to win races. He ran with many different co-drivers, including John Mills, Tommy Grunnah, Steve Shelton and John Lloyd. At Sears Point, he was partnered by a friend, Jim Cook, who tried to qualify the car. Sadly, he suffered from a heart attack and died during practice."
Four-time Daytona 24hrs winner Bob Wollek was killed on a bicycle at Sebring . . .
http://en.wikipedia.org/wiki/Bob_Wollek
"On Friday, March 16, 2001, while leaving Sebring International Raceway following practice for the 12 Hours of Sebring, Wollek continued a tradition of cycling between the circuit and his accommodation, which took him west on Highway 98. While he had been riding close to the edge of the pavement, he was struck from behind by a van driven by an elderly driver from Okeechobee, Florida at approximately 4:30 p.m.[8][9] He was transported to Highlands Regional Medical Center in Sebring and was pronounced dead on arrival. As a result, the driver was stripped of his license. Wollek was due to start in the Petersen Motorsports Porsche 996 GT3-RS with Johnny Mowlem and Michael Petersen,[9] however out of respect the car was withdrawn from the race.[10] On race day, the organizers held a one minute silence in memory of Wollek. Prior to his death, he announced he would retire from racing to serve as an ambassador for Porsche, and was due to sign this agreement upon returning home after Sebring."
And then there was Peter Gregg (BMWNA 1976 factory driver in a CSL) . . .
http://en.wikipedia.org/wiki/Peter_Gregg_%28racing_driver%29
"Peter Gregg died December 15, 1980 at age 40 shortly after getting married to Deborah. The official finding was suicide. Reports at the time suggested that Gregg was suffering from a progressive and incurable nervous system disorder which would have slowly degraded his physical capabilities and would have eventually been fatal - and that this, in the context of his perfectionism, was what motivated his suicide.
At the time of his death Gregg had achieved a reputation as one of America's greatest and most successful road racers."