I found this pretty well useless in removing road film. I suspect the same goes for other pressure washer car detergents. Following directions to leave it soak does not help.
I found the best way to use it is pour it in a bucket, add water and wash by hand. No pressure washer needed!
Mick Does Not Recommend This Product
Most consumer-grade pressure washers deliver detergent through a siphon tube system. This moves the water/detergent mix through the pump, so the detergent can't have anything in it that would damage the pump and seals- that's what we mean by "pressure washer-safe".
Some kinds of gunk just need elbow grease to move it off the surface. In those cases a pressure washer will wet it down quickly and rinse it thoroughly, getting the job done sooner.