In a statement on his website, he added: "They have made it very clear that the risks involved in further racing are too great and could be detrimental to my long-term well-being.
Nevertheless, Heidfeld has scored points in five further races, and lies eighth in the championship two points clear of Petrov, who is in his second season in F1.
Defending champion Tom Boonen crashed out inside the opening 20km and will not ride in any further races this spring.
The younger Schumacher will have another chance to impress in two further races at Oschersleben on Sunday before the championship continues at circuits including the Red Bull Ring, Spa-Francorchamps and Hockenheim.
Audi are determined to achieve at least one further race win in the series, McNish noting that: "We won the big one, the Le Mans 24 Hours, but for me personally I'm eager to finish what has been a largely frustrating season on a high note".
The next round of the series is at Phillip Island next week, with further races at Motegi in Japan and Valencia in Spain still to come.
There are further race-dependent differences in income by different levels of education, as well as differences in neighborhood poverty at different levels of income.
This was a man with his mind clearly set on overall victory from the off and it was an approach that would pay off in spades that season, with further stage race wins in the Tour of Romandie and the Dauphiné Libéré before the Tour.
Brabham was the more successful driver and went to the United Kingdom in 1955 to further his racing career.
In fact, in every distance race further than 400m, the world record times of wheelchair athletes are faster than their able-bodied counterparts.
Since only 38 and 58 persons self-identified as Hispanics and "other race", respectively, we were unable to include them in further race/ethnicity specific analyses.
