Another vote for Zaino here. I have to park outside (offstreet at least, thankfully). I can't do waxing 1 day a month, so the 6 months a few layers of Zaino will last does the trick for me.
You can always re-apply Zaino CS midway through your 6-month cycle after a wash as well. Keeps the other stuff on.
'11 550i, but it's too big for me
Prev: '08 E92 M3, '04 E46 M3
Waiting on redelivery: 2015 F80 M3 SO/SO MT, picked up at Welt 7/1/2014, dropped off in Antwerp 7/11