Reports are coming in from everywhere (and I can attest to this as well) that drunk driving in Grand Theft Auto IV can and will give you motion sickness. The blurry visuals, wobbily camera, and Niko swerving and careening all over the road when your mind is saying "I'm driving in a straight line! Why are my eyes seeing something different?" all contribute to the feeling of motion sickness. I have a full article on videogame motion sickness here:

Videogames and Motion Sickness

And if you just want some quick remedies, follow this advice:
Ginger pills. You can find them in the vitamin section of your grocery store. Sea Bands. Wristbands for seasickness work just as well for videogame motion sickness. Combine the two for super motion sickness fighting power.