Some various Super GT shots with the DA 55-300 (non-WR version):
The lens is a joy to use for Motorsports due to is small size, especially when you see Canon and Nikon shooters lugging around their heavy lenses.
Those professional sports lenses might be far superior in image quality I am sure, but not needed for my limited abilities in any case.
Even though the lens is not the fastest for focusing, I think only for 1 out of 100 shots I actually missed the focus and had to wait for the next car or the next round.
For those types of panning shots (where you want to stop down anyhow, to achieve a slow enough shutter speed), it is the perfect lens!