cars belgium francorchamps spa 1971 24h other races touring amg benz mercedes hans heyer hi res pits pitstop a4 clemens schickentanz porsche prototype sports 1000km 1973 911 carrera kremer oldenkott front germany guenter keller nuerburgring paul steckkoenig fitzpatrick john a3 many mechanics two blur emblem engine light refuel side speed start track austria bmw carlos celebrating ford gaspar gijs kersten lennep lola peter podium rear technical tools tyres van zeltweg zoom