hi Tom, great to have another michiganian on board. you work up at msu as a faculty or just working in lansing?
1.8t quatro is a really good choice imo. you already have a boxter, so you don't really need another lowered rwd for winter. my 330i was great w/ snows, until we got over 5 inches.. then i was just floating above the snow, not going anywhere...
i was debating btw 1.8t and a 330i and opted to pay 15k more for my ride, so that's where i stand on the matter. i hated the a4 3.0, however, as it was slow and heavy, and didn't see a point in dropping all the extra cash for the bigger engine over the 1.8t.
i'm not a big fan of awd setup outside of audi's. bmw's is good from what i hear, but i really think rwd bimmers are the only way to go. as for the g35 sedan. first off, its way uglier than the coupe counterpart, and second the awd goes off after hitting 26?mph or something like that. i'd rather have full time awd, not "we'll turn off after a little bit" awd.
i've been meaning to test drive the TL and the tsx. they are both nice rides, and pricing is really good. (i drove a friend's TSX w/ auto. pretty nice, altho i wished for a manual to tap the 200 horses..) also consider that if you want a nav system, honda does make one of the best in the market. something else to think about i guess..