Many thanks Nick - your comments are very helpful. One quick question though - what's a fixed seat? Is that a forward facing child seat from this website?
Child Car Seats : Types of Child Seats
If so I'd say we're OK and good to go - time to test the 3.0 again and the 4.2 to see if I can be sufficiently tempted!
P.S. - couldn't agree more with the good taste comment! Spot on - so much more classy and unpredicatable than those X5, Cayenne, ML driving sheep!