I'd just like to add for shooting motorsports, don't worry about chainlink fences at all - put camera on manual focus and shoot through them, they won't affect the shot assuming you have your aperature more open and not stopped down so the DOF is on the track where it belongs. Just need to time your rhythm so you shoot between any supports, because those are what will mess up shots.
Generally the highest shutter speed you want to ever be at will be around 1/250 or so, go as low as you can possibly go to get good shots, probably no lower than 1/80 or so, depending on how good you are with panning.
And in using a 4/3 system, these are the notes I took from the 50th 24 Hours of Daytona in 2012:
A. Infield Carosel 1, entry: 50mm & 135mm
B. Infield Carosel 1, exit: 135mm & 180mm
C. Infield Carosel 1 exit to before gator: 50mm, 135mm, & 180mm
D. Gator: 135mm
E. Infield Carosel 2 exit: 135mm & 180mm
F. End of straight after infield carosel 2: 50mm, 135mm, 180mm
G. Banking after infield exit: 135mm, 180mm, 300mm
The lenses I had with me were 24mm, 50mm, 135mm, 180mm, 300mm, and 500mm OM Zuiko 35mm film lenses.
Keep in mind 4/3 is 2x FOV factor compared to 35mm, so double to get equivalent 35mm full frame focal length lense range to use, then factor down for whatever sensor size you are using. Basically looking at 100mm-500mm 35mm equivalent lens range for most on track use, and a 300mm-400mm 35mm equivalent prime would be a sweet spot if you are looking for a single lense that would be worth it for motorsports (due to funds.)
And needing high FPS to shoot motorsports is not a necessity. It can be done well with manual focus, manual stop lenses in one shot-one kill mode...just takes more effort.
All manual and prime is how I like to shoot, no matter what: