I have a dumb question ...but being new to all things Audi, I think I should be allowed some elbow room to ask a few. anywhooooo.. Whats this rectangular black 'bottle' under the bonnet of my 09? What's in it? What does it do??? P.S: The correct answer will treat the above as 1 question - thus leaving me scope to ask more 'dumb' questions in future without the risk of being labeled a 'dummy'. Thanks.