Is your car in good shape? I used to get terrible headaches and nausea after riding in my 15 year old vehicle.

I got rid of the beat-up old SUV a month or two ago and now drive a small convertible. I no longer have major issues after a long drive, although my neck does still hurt pretty badly. The headaches are gone, though.

I have also found that it's worth it to leave early and take a longer route if it means you can avoid heavy traffic, areas of the road that are under construction, etc.