I have heard of people with the VW beetle using carseats in it. I have never been in a VW beetle and really don't know much about them, but some friends of ours just got rid of theirs and mentioned that it only has 2 seatbelts in the back
Anyways the safest spot for seating spot for a baby is the back middle but would be safe outboard as well. If you test drive one get back in the back seat and see how muc room there is, also think about how convienent it will be getting a baby in and out of the back seat. I think it will just be a personal preference
Good luck deciding
Just remember that they have small trunks so you would also want a small folding stroller.