Each car has 3 bench seats, meant to hold 2 people in each bench. If you are 5 adults, you would have the entire car to yourself. If you are a mix of adults and children, depending on the age of your children, they might have you "buddy up" two adults and a child. Each bench seat is pretty generous size. The last time we ate there, they put part of our group (two adults and a 4 year old) in one bench seat together.
Everytime we have went as a party of 3 or 4 adults, we have had the front two rows of the car and had "hitchhikers" in the 3rd row. Every time my husband and I have dined here just the two of us, we have been the "hitchhikers" in the 3rd row behind a party of 4 strangers.