We enjoyed the ride, and yes if you get motion sickness on teacups it is not a good move to try it. The cars go so close that dd was certain that sometimes they had hit, which made her laugh more.
I have written a bit about the five times that we went on Cars on the post about the Soft Opening, but I do not know how to do a link to it. Also, if I get a chance this evening - now we are home (well at work at the moment) - and can figure out how I will try and add some photos, none in action but of the queue and us sitting in the cars.