I don't use any kind of soap or fabric to wash my X. They are all abrasive to a degree.

The safest approach to cleaning your vehicle is to use just plain old water from a low-pressure water hose to rinse/spary off the dirt. And it gets it just as clean as any soap or fabric.

The idea here is to expose the paint job to the least friction as possible. Friction is created when rubbing paint against a cloth for example or having the paint come in contact with detergents.

Over time this kind of friction will wear out your paint's finish and shine much quicker than it would otherwise.