Dull question I know, but can you get kids seats (I have a three year old in a full car seat) in the back of a GranSport?? It used to fit in the back of my 997 but there seems to be a lot more room in the back of the Maser??
I would take the seat, when test driving. You will have no problem with space, but I know from experience the bucket seats (in the rear) can cause problems on some seats.