Beyond the obvious fuel type and the $4500 difference in the base price, what are the differences between the gasser Golf and the TDI. I know that the TDI gets a "performance" setup, complete with 225/45/17 wheels. I also believe that the TDI get an upgrade touch-screen radio (accessory?) controller. What are the other differences? Spoke with the dealer today who only had the gasser to look at (and that only arrived this week), but he was not exactly clued in on the details. Anyone got the straight dope?