"and it is amazing to me that those engines are so little implemented in the USA."
Why is it amazing? The green libs in this country won't let us buy them because they 'pollute too much'. VWofA quit importing TDI's at the end of last year because it had to meet EPA fleet emission standards and couldn't do it by adding more diesels to the tally for 2005. The greenies would rather promote overcomplicated hybrid Toyotas that claim to get 55 MPG but only attain 35 in the real world ....
I drive a TDI. 44MPG real world, 50MPG if I keep my foot out of it.
Also: I agree with Wil. Audi is what Porsche used to be.