I've used this a couple of times now on my truck and have been really pleased with how well it works and how long is lasts.
You just wash as normal, rinse and before you dry spray this and then dry. It wipes right off, no effort and leaves a nice shine and wax feel.
I used it last week and the dirt from driving on the freeway while raining just rinsed right off with the hose when I got home. I washed again today and it seemed to make the washing go quicker/easier.