Everything I've read on the internet so far seems to suggest that babies shouldn't experience travel sickness until they're two. Took 7 month old DD for longest car journey so far yesterday (50 mins, urban streets) and she was sick at the end of it. She seemed fine beforehand and afterwards - was smiling minutes later so it didn't seem like a bug.
I was terribly car sick as a child but not sure whether it passes on.
Anyone any experience of young babies getting car sick?