I would be tired too if I ad to recite the same speech about the car every 10 minutes. Even when no one is around, there they are talking away.
Parkerman, I think you will be happy about the Chicago show. I always went to NAIAS as Im originally from there, but began going to Chicago. McCormick is a much larger place, so the crowds dissipate fairly well. As for shooting with the D40, make sure you bring a lot of memory and only shoot in RAW! With all the different lights they had on each car I had to do a lot of WB tweaking. These are some EXIF's I was getting:
f7.1, 1/200, iso 400
f6.3, 1/160, iso 400
As you can see, with the iso at 400, I was getting good enough light to remove hand shake.