I use Kalgard Prep & Shine on my car first when it's really clean. This makes it so dirt and dust can easily be wipe or falls off. Usually after a days running all I need to do is grab the air compressor and blow off the car and combined with the Prep and Shine almost everything comes off. This is not going to work in motors and anything electronic. But for the chassis roller it self it works great.

For electronics there is some electronic spray cleaner that was mentioned in the posts above.

Also another good cleaner is some diluted simple green.