I went from a 2008 Lancer Evo X (very slightly modded, 35,000 miles, MT) to a 2009 BMW 335xi (29,000 miles, MT) a few months ago. Both cars are AWD, 300ish horsepower/torque (my evo was closer to 360)
The BMW makes for a much nicer/more comfortable highway cruiser, slightly better gas on the highway, about the same or slightly worse <55mph, but honestly, I don't think It'd it's worth the extra 15 grand new price difference over my evo was new...
That said, do I think it was a pretty nice upgrade for 6 grand (the price difference between my trade in and it) I was amazed at how much value my Evo maintained...
In my BMW I get compliments from car guys and random ladies
In my Evo I got complliments from car guys and teenage boys
I have had to drive both cars through lake effect snow conditions on weekend nights (think sunday at 2am) when they weren't plowing the roads... both cars do well in 6+ inches of snow although I think I'll give the edge to the EVO, although I think that's mostly because it had fresh blizzak lm-60s while my bmw is using the MUCH older design and fairly worn blizzak lm25s... both cars will plow through any amount of snow, but the evo felt more stable when moving from hardpack snow or unplowed snow into slush at 55+mph (ie: passing people on the highway and having to cross the dangerous section between lanes.
Regarding everything people have said about BMWs... there is zero reason at all to continue to use the stock tires after they've worn out... buy some real tires and just carry a can of fix-i-flat (and a small air pump)in the trunk... and roadside assistance through geico is like 20 dollars a year, AAA is even cheaper I think if you need a tow (your tire doesn't just have a flat, but completely shreds because you drove on it flat or something).
Although you don't need the new car anymore, I think that's was pretty good price deal for a 2008 328. Features to look for in buying a used bmw, comfort access (not needing to put the key in the ignition, is very nice wasn't an option available at all on the very first 328s only on the 335s, I think 2008 was the first year it was available on the 328), so preferably you'd want pick one with that, Also the comfort access battery is a simple 5 dollar replaceable battery at radioshack and will last 3 years or so, the normal key is a rechargable battery and eventually it will barely have enough charge to last when it's not plugged into the car. Almost every BMW comes with the "premium package", which is the built in garage opener and auto-dimming/heated mirrors (and leather seats for the 328), it's kinda a nice feature that I don't think I'd ever want to give up now that I have it, I used to HATE trucks that would ride my ass... in the other lane... shining their lights right into my side mirrors. People do that shit all the time, and it doesn't even bother you if your side mirrors auto-dim.