Astrid - thats what I wanted to do initally, and i think i still do - have the baby seat/capsule in the middle. Do the seats both fit easily next to each other - we have a vx commodore wagon.
It is a tight fit. I found I had to re adjust the seat quite often to keep it sturdy. It did not help that DD1 would often pull it about when she moved about the car in search of out mints The seat is sturdier when on the side, rather than the middle.