A di**y seat is extra seats added to a car after market. We have seats in the back of our ford station wagon. We originally got them for when we have other peoples kids with us which ends up happening fairly often. I am now pregnant with number four so they will be used more often. I suppose they aren't as safe as seats in a people mover etc, however, we have more space behind our seats than a lot of four wheel drives or people movers do. The rta should be able to tell you where to get them from. In Sydney you would be looking at at least $1500.00 depending on they type you need.