Is test track in any way like a roller coaster? My DH suffers a bit from motion sickness and did not feel well after Space Mountain last time we were there.
depends... if she can't see over the seat, she may feel sick? I see some kids who are kinda short in the seats. It is twisty at times, like a race car.
If your DH does fine driving around curves this should be fine. Just keep in mind that the car does speed up so those curves do give you the feeling of being on a mild roller coaster. There's also a spot that tests the brakes so there's some sudden stops. Our friend's son who has a very sensitive stomach and gets very car sick didn't like that part. But I get motion sick very easily and I did fine on Test Track. It's not like Space Mountain.