And as far as the shoe thing, I can still see how less experienced drivers (who don't have hours and hours of stunt driving behind them) could have trouble making split-second maneuvers while wearing tiny high heels that could easily slip off a brake pedal. Although I guess that could be down more to the driver than the shoe...
They explained in the aftershow that, since they are very experienced drivers, they deliberately designed the test course to challenge them to the limit of their abilities. So that should've pretty much cancelled out their advantage.
Besides, the point was to compare their performance in the awkward shoes to their performance in normal shoes in the control run. That cancels out other variables like the drivers' skill level, because it's the same driver running the same course and only the shoes are different.