Once fall hit and it was too cold to wash the car I used the this waterless/wax product over a boatload of coats of Zaino and it worked very well. It is not for getting significant amounts of crud off your car though. I'll use this again in the spring until it's warm enough to wash the car then reapply Z2.
http://www.properautocare.com/cp-32.html
Speaking of spring this is a rough time of year. I haven't driven the Boxster in almost 2 months and I keep waiting for this crummy weather in the NE US to let up.