Here is a link to an article about the new 2.0TDI-170 TT. It gives more details of the new common-rail TDI-170 engine. No doubt it will be the same engine that will used in the new generation A3.
http://car.kak.net/2008/04/30/the-audi-tt-tdi-performance-and-efficiency/
http://car.kak.net/2008/04/30/the-audi-tt-tdi-performance-and-efficiency/