I have not washed it myself but taking it to the local car wash (really nice hand wash place), they do not know enough about the car and it requires me explain it each & every time.
First you explain how to get into into the wash bay, then as it comes out the other side, someone esle gets in and is totally lost :o on how to pull it up to dry!
Of cource I love talking to people about the PRIUS

but only those who are really interested, the car wash kids are baffeled even when I leave the valet directions sticking up on the dash! :unsure:
When they finally pull it up to dry, I go over and pop the hatch (so they can dry it well), and I take the key away so it won't strart if they try to pull it up again (too near a very busy street to trust them).
They are baffeled by the Smart Entry/Start, the shifter, the power button... really everything.
I made-up a sign that goes over my LCD screen that says;
"Please
do NOT clean
screen".