I haven't done it to either of my c4s I don't feel there is a need. All the components can be wiped individually or reached etc with spray bottle and rags but I have done several cars in the recent years.
I use diluted simple green and water. Dishwashing brushes (various ones). On a cool/cold motor I just spray the stuff on and let it sit. Then I brush gently to loosen dirst. After that with a hose turned on for little flow and NO nozzle on it.. just let it spill over the motor taking the grime away. No pressure at all.
This was my old 01 z28 I picked up. It looked worse but it was raining and it got the front wet but it was all white with dirt/grime buildup too.
SImple green.. brushes.. Just start brushing away
