Paul,
I used the Graco when my son was a newborn. There was a base that went with it, but I did not use it - we used it in the other car. It fit well for the baby, but the passenger in front was a tad uncomfortable. Remember all newborns must face the rear and sit in the back seat until they are 1 year old.
Now he is seven months old I have him in the Cosco - Alpha Omega Car seat. This is a much larger car seat. Still rear facing, and since it is at an angle the passenger is even more uncomfortable than before.
As I mentioned earlier there was a base that came with my Graco, well a base also came with the Cosco. I found this base too large to use in the MINI. Others may disagree, but I was able to sucessfully install this car seat securely. It does not budge with the ISOFIX LATCH system.
Apart from that I can still fit a passenger behind me, and the baby holds on for dear life when I am behind the wheel
I hope this is the kind of information you are looking for. Let me know if you have any other questions.
Rainey