I have a 2010 Beetle Final Edition COnvertible...I havethe white leather interior which is supposed to be "washable," however, I put a catalogue on the car seat and there are black marks where the catalogue was. Also, I had a car seat in the back and the leather got dirty. I would like to sell the car but it definitely needs to be cleaned up...I have mats on the floor so the carpet still looks good. exterior sides still have the original plastic and convertible top covers are both still NIP...Windshield has been replaced due to rocks...A couple of nicks in the front from ice and a ding in the bumper on the back from some crazy mall lady without a drivers license. HOw do I clean the leather so it looks nice and is there anything else I should be concerned about? Look at?