My question is about ambient temparature. I would have thought that regardless of the outside temp, the coolant temp should be more constant and not be as affected by the ambient. Perhaps I am way off base here. Anyone have any good scientific or simple explanation for this? Thanks everyone for answering these questions. The engineer in me just does not want to let this rest.

FYI, my friend in Hawaii has a 99' e430 and it always seems to run about 85-95C no matter what he is doing. The temp in Hawaii is always around 70-80 F.