car washes shouldn't be a problem. try to go to one of those brushless places because the brushes can be a little rough on paint IMO.

oh and if the car is that dirty don't forget to take a picture first and post it

 

Don't use automated car washes if you have a big wing. Plus, it's a little rough on the paint. Your best bet is to find one of those gas stations with attendants/employees that do a hand wash for you.

 

I put my car through the touchless/brushless automated washer at the local SuperPumper once a month or so; it does not physically touch your car in any way (it uses light sensors to position the height of the sprayers). The Blue Coral soap is decent, but can't get off tar and bugs, so I detail later at home. One part of the car wash is pretty scary -- the air blower at the end designed to help dry the car is so strong that it totally deforms my hood scoop and aluminum hood! Luckily, being resilient materials with good "memory," they snap back into place. I drive the hood through real fast and then drive slow once I reach the steel parts of the car (roof and rear trunk).

However, I also protect my finish with the Klasse Twins every three months, so my finish might be a bit more resistant to the harsh soap. (Search on Klasse here for details).