I have a real issue with keeping my Stang clean. It's black
, so for the longest time it was proving to be impossible to get a spot free shine. Then, I finally found a combination that works....even if it sounds ridiculous.
Now, I use Rain-X wash and wax, making sure to wash in the shade. Then, I grab the electric leaf blower, believe it or not I swear it works, and I blow dry the entire car. The process takes about 10 minutes, but I don't have a single scratch on the paint job and it doesn't spot either. Then just slap some Armor-All spray on tire foam on the wheels and you are good to go. One thing I don't like about the tire foam however is that it typically drips down onto your rims and, upon drying, kills the shine.
So, I have to take a slightly damp rag and go back over the rims. It's a pain in the a$$, the wash job typically only lasts for about three days, but it's the best I can do for a black paint job....and it looks great when it is clean.