I was told by my R8 tech and good friend NOT to wash the engine with a pressure washer. It can get into the spark plug modules and cause arcing/sparking/shorting. Be careful around the heads if you're doing this.
If you live on a dirt road or have a gravel drive (which I do and did for 25 years), expect a dusty engine bay.
I always just wipe everything off with a damp cloth.
When ever I go through (yes, I go THROUGH) a car wash (it's the same paint and surface as any other Audi, it's NOT special, regardless of what you want to believe...), I always ask for a damp cloth and wipe down the engine bay myself.
I've never seen any car was offer an engine cleaning as part of the drive through service, so I don't believe, just because the engine's visible, that it should get special "oh, we'll clean that for you" from the guys that bust their butts at the car washes.
Man up and wipe it all down yourself.
