Primarily used my 1D Mark III with pretty good success. Night shots are at ISO 3200 with no noise reduction and are somewhat noisey but better than I've seen from other cameras. So pretty happy with those. For previous motorsports events I was using the 5D Mark II and 1D Mark III but for whatever reason, the 5D Mark II did not hold up as well in the AF department as it had in Atlanta. Not exactly sure why, I hadn't changed any of the settings between events. I'm sure it was just me haha
Anyways, here's a few photos I took. I have a bunch more on my blog site if you care to see more linked at the bottom.