Cliff and TC,
I also wash the cars outdoors the driveway, (with outdoor hot/cold mix as stated in the previous thread), as long as the temp is above freezing. Yes, it's cold, and my hands/arms and feet get soaked, especially when washing the wheel wells and undercarriage, but I just grin and bare it!
If your garage is unheated, drive the car defore putting it away (if the roads are clear enough not to mess up your efforts) to dry the undercarriage, wheels brakes, etc. Apply the brakes and the E-brake to dry them (preventing an E-brake lockup which I experienced last weekend after washing my Z8, and then experienced a temp drop below freezing
)