I was shooting cars in aperture priority (Av) mode with aperture set to 8.0 or 9.0. After closer inspection on the big screen it seems that these aperture values are a bit too small. I will try with a slighter bigger settings tomorrow.
I also have both B&W polarizer and lens hood on. Polarizer does improve the images a lot. Lens hood protects mostly from the dust which there is an excess of. :) Light conditions still seem a bit tough to me. Even the afterlunch sun is very bright giving harsh shadows. Shadows from trees along the stages make it look kind of stripy (shadow, no shadow, shadow, no shadow…). On-camera flash is not strong enough to fill the shadows around the car and good viewpoints are hard to come up with considering the safety guards, spectators, stage track shapes and locations, and my ignorance. :) More to shoot tomorrow…