Engine parts, especially on newer cars (90'* - current), aren't nearly as tempermental as people would have you believe. As long as you dont directly spray the electronic parts you will be fine. Foaming tire cleaner works excellent for the plastic stuffs. For hardcore grease removal Gunk'* Engine Degreaser will just eat sludge up, but a product without so much strength would be something like orange cleaner or that green stuff. I also found this link a while back although I never actually tried it.
Also do not spray into your engine with a high power washer, such as would be found at a car wash, use a garden house without any attachments. Very gentle.
Don't waste your money on those armor all wipes. If you have a business just get some cotton terry cloths and wash em once if they have lint on em and they will work for tons of things.
Oh and polish his cobra. Don't just wax it.