Ok, I know this isn't motoring in the strictest sense but still related.
Our two year old daughter gets travel sick on almost every journey we take, whether its 15-20 minutes to the supermarket, or two hours to my family. Always uncomfortable, and quite often we find ourselves cleaning up a lovely mess. I've had to strip the car seat down more times than I'd like frankly.
We currently have a Honda Civic Mk 8 (space ship looking one). It's a great car but she sits fairly low down in the back, and in all honesty I'm not sure how much she can see out the window or even how much effect this is having.
So having read up, it seems the travel sick is caused the brain getting mixed signals about motion from the inner ear and eyes, as well as nerves etc. Some quick searching suggests many people suggesting looking forward through the windscreen helps, but I don't think so - we had her in the front of the car for a short while and she still threw up a few times.
We were in Colombia around 18 months or so ago, and during that time she was travelling around in the mother-in-laws Toyota Land Cruiser. She wasn't sick once (she was there for nearly three months as well), despite the high temperature and non-opening rear windows. My wife also quite often feels sick in the back of most cars, but doesn't suffer from this in her mother's car.
I think we will take her to the Drs and see what they say, but I'd rather not rely on medication for every single trip if I can help it. Advice suggests stopping every time they start to feel sick, but that just isn't practical; it'd take us an hour to get just to the supermarket!
I don't really want to change the car, but it's on 183k miles, so it won't be the end of the world. I don't want to buy an SUV if I can help it, but if it turns out to be the only cure, then I'll do it. Interestingly, some people suggested they feel less sick with sports settings turned on (not necessarily in SUVs) to make the ride more bumpy rather than a nice smooth trip. I'd have thought it was the other way round, as the Honda is quite bumpy and crashy.
Any reference to 'people' generally means online forums so take it for what its worth!
Any thoughts appreciated, or links to actual science / studies surroundng this to try and understand better. Fortuantely, I never experrienced this much as a kid (or at least I don't remember it being the case), although I was playing in the boot of a giant Volvo most of the time when I was a kid.