Kitty, my DD gets that way if she sits in the back seat of the car, or if the windshield is curved too much at the sides...never close your eyes in the car--it adds to the vertigo. Try to keep your sight glancing at a horizon somewhere every 30 seconds or so--it gives your sight stability.
Maybe closing one eye would help some--your eyes may not give your brain equal information and that might be causing your vertigo.
Talking to an eye doc or maybe look up the problem on the internet might give you some help. If sitting either in the front or back seat makes it worse, try the opposite and see if it is reduced.

Arrgghhh, the aggravating sxs that this stupid disease gives us...