You should have no problem in the GTA in a Z4 with good winter tires. I drove my car in everything but the two big storms we had last year and the only reason I didn't drive it then, was fear of someone else hitting me. In anything over 3" - 4"'s however, the car will become a plow - most BMW's do.
What year and model are you looking at?
2006 Z4 M Coupe, Interlagos Blue
- Supersprint Race
- OE STB
- DZ CDVD
- RE CS
- H & R Sport Springs