I agree with putting 4 winter tires on the car. Personal experience...
With my Neon, I used four, used winter tires with steel wheels that cost me around $240.00 CDN. (2 Canadian tire brand, 2 Pirelli 100 winter tires)Mismatched; yes, but they made a world of difference.
With the P5, I just bought a set of Hankook IceBear W300's and al I can say is WOW! The cheapest of the lot in the size I needed, but with great, and as I found, true reviews. These tires have an H speed rating ( although on snowy or wet roads, one would or should not be driving near the speed limit of the tire...(210 KPH) are VERY smooth and VERY quiet.
I paid $500.00 CDN for a set of 195/50/16's and the difference between these and my all-season tires is amazing. With the all seasons (90% thread left) I would slide everywhere, and stopping on each block was an adventure... with these, I can still press the pedal fairly hard without activating the ABS. Also, I was able to make it up quite a few steep hills covered in loose snow-over-ice.
$500 for a set of witner tires might sound (or be) expensive, but I know that the car handles better in the snow and ice. Additionally, this set of witner tires, will probably last me anywhere between three and/or four seasons, simultaneously elongating the lifespan of my all seasons...so I win..at everything...
Be safe, spend the money...even old, used winter tires all around will be better than your summer or all season tires.