Yep, I think the New Smyrna little 500 is scheduled for Dec 27-30, so if the disney race could be right after that, that would be eaiser on families who will have to travel a ways. Plus, winter is much better to visit Florida. In the summer, Florida is "walk-out-the-door-&-immediately-start-pouring-sweat" time. A winter disney race would be much more comfortable (especially for those not used to Fla heat).

Like Scott F said, Apr/May are spring break time in Florida, which would cut down attendance for the race. And for those who want to visit disney & ride the rides, you'll get on a lot quicker (no terribly long lines) in the winter.