umm i got an 09 bmw 328xi and about a year ago i was facing the same decision...
In the summer, youll be glad to have a 335i
In the winter, youll be fucking wishing youd bought the 328xi.
Ive driven a 323i in the winter and it was horrible. Slipping everywhere... So i mean if you get the 335i in the winter, you're risking alot and more likely to have an accident...
plus you save gas; but the 335 is funner to drive.
You have to weigh your options funner and more respect (335i) vs. safer winter driving, less prone to accidents in winter, less money wasted on gas, and respect. (328xi)
Btw are you getting the coupe? there selling 328xi coupes for 30 to 35k ???? i bought mine a year ago for like 40k