Mr. Clean auto dry system!
i prefer to use the Mr. Clean auto dry system..i swear by thMRat product. just pre-rinse with the 3-in-1 spray gun (dial set to regular unfiltered hose water), then set dial to "soap" setting, i also use a wool hand pad to gently scrub, the last step is to turn dial to "rinse" using the dial and spray away dirt and soap with filtered water. dries like glass with NO streaks what so ever..the best and only product i will use on my bimmer...got mine at a local parts store for $19.99. refill soap and filter around $4-7 respectively.