As for cleaning the engine, I have been doing that for years. I donít worry so much about others saying it could kill your electrical systemÖ of course you have to be careful where you spray water. I donít use high-pressure water (i.e. coin operated car wash). All I do is take the air filter housing off. Cover the intake and air mass with foil and plastic wrap and cover all electrical component with foil or plastic. Spray engine degreaser into the warm engine. Let it set for 10-15 minutes. If too much dirt, use a small parts cleaning brush to work away oil deposits etc.. with a garden hose and nozzle, spray little stream over areas with large dirt deposited. Dry the water with a rag as much as you can. Remove all plastic coverings. Put everything back together and run your engine for few minutes to dry it from water. For a final touch of shine, I spray tire cleaner over all plastic parts and air filter housing (a trick I learned from Jim. See item#21 on his link: http://pages.prodigy.net/jforgione/MB_S500.html
). As you can see from my pic above, you get very nice shine and no dirt is attracted to your engine.
Nice catch! E420s are extremely fun to drive and pass other cars. It has so much power yet very elegant. I also like the older look with wide headlights much better than the new rounded look.