S.C.
My son started getting car sick around the same age. I noticed it was when I let him drink milk in the car. Now I let him eat crackers (goldfish) in the car, but nothing to drink. I also bought him Sea-Bands for kids. They're wristbands for motion sickness. And I took the headrest off the seat in front of him so he could look out the front window instead of the side. He's 3 now, and hasn't gotten carsick for about a year. I don't know if he outgrew it or if it's because of my "system". All I know is my car smells a lot better! Good luck.