Well I've been involved in drifting for the last year or so, and now that I'm decent with a camera I've been able to get on-track. My first event a few weeks ago was definitely an eye-opener for me...I basically learned how to pan on-the-spot. I talked to a respected photographer in the sport and he stressed getting a f/2.8 lens to help speed up the focus of the lens. Would the 2.8 really make THAT much of a difference over a 4 or 5? Here's the best two shots I've been able to get with my 55-200 f/4-5.6.