Ok, if I get a 300E or 320E as I plan, I have a concern with the above two items.

baby seats in the back seat - any need to put something between them and the seats in order not to scratch the leather? What about the indentation that the baby seats could leave on the leather since they are strapped soo tight with the seat belts?

bike carrier - I do mountain bike riding and will need to transport my bike. I don't know about attaching a bike carrier to the rear trunk lid (you know the temp ones)....how do you guys do it?