Has anyone everseen a car style pressure washer at an airport
anywhere?

I saw one being used by the owner, but it wasn't provided by the airport. The
aircraft was a Cessna, and the owner said he only used the washer with low pressure
to apply the soapy water. He did the actual scrubbing by hand.

I think someone posted here a couple of weeks ago that the delta between
enough-pressure-to-remove-the-dirt and enough-pressure-to-remove-the-paint was
small. Having had a couple of non-aviation mishaps with my portable pressure
washer, I can believe it.

Dave