Well, I'm reading to determine if a 323i 6MT is a viable Canadian winter alternative to a fwd TSX, for all the drivers in my family: I found out this morning that is can be, but snowtires are a must. My question, however, was if the 325i was up to the task, not the tires.
Five inches of snow fell last night, so I took a 325i AT, with OEM all-season Bridgestone Turanzas (205/55-16) for a test drive along some residential streets, up and down some hills, with lots of stops and starts, and turns everywhere to test traction. The 325's traction control, stability control, considerable weight and weight distribution ment that the car could do whatever I wanted, and would go wherever I pointed it - no problems, no drama, no sawing madly at the steering wheel battling understeer or oversteer around corners, no wildly spinning tires spewing up snow everywhere. I was impressed. I know what most people think of the Turanzas, but getting stranded, or putting the car into a curb was just not going to happen (well, I wasn't going that fast and I had CONTROL). Sure, starting on a hill, the TC would cut back engine power - a lot - but the car would just start moving, and climb.
I would buy stock-size snowtires, especially because I would like as much traction as possible, and wouldn't want to get caught in the middle of an intersection, with on-coming traffic.
On the limitations of hi-po tires: even my 4500lb minivan had snowtires, where it became a tank which didn't like to stop. My Protege with snowtires requires much more "skill" to drive in the snow, and while it's predictable, it is sloppy. Well, I'm glad I now know what works.