Looking at the race resuts, perhaps the stig really isn't the superhuman his reputation says.
After 23 hours, the best lap by Top Gear (i.e. by the stig) was 2:16.2. The best lap by Saxon, using another BMW 330d was 2:15.2. Top Gear's best lap was done on their second lap, when the stig was at the wheel. Although IIRC, they were only on 5 cylinders at that point.
True, however even though they had the same model car they didn't have the EXACT same car, they could of been on different tires, the saxon engine could have been putting out slightly more power, there are just too many factors to consider to say such a thing bout the stig