If your friends have 250k cars, they sure pay more for a mirror.....
Still $220,- is an expensive car wash......
Also a car wash is bad for the roof, just wash the car by hand, don't wash the roof. It gets damp by the waterspray, and drying it with a microfiber towel is generally enough to keep it clean also.
MAybe once a year (or every 2 years) clean it with an interior cleaner (brush it in with a hard brush, and vacuum it out with a shop vac that can handle liquids (also called an extractor in car detailing words....) and after that clean with water:
After this, you treat the roof with a spray that weatherproofs the roof (the same as the stuff you waterproof tents with), like this stuff:
This also repelles dirt and maybe gives some UV protection.
Be sure if you use these sprays, to mask off all the rubber seals (window seals etc) as the glass, bodywork etc, as it leaves a pretty tough residue. So make sure only the cloth gets covered in this spray (spray lightly multiple coats, in the shade, preferably inside in the garage)