You buy a diesel car for one thing: FUEL ECONOMY. You buy a TDI for another: VALUE. I have experience here.
Why wouldn't you buy the Passat TDI instead? Same $$$, more legroom, etc. Hey, $25 K, 6 speed manual or auto... and 45+ MPG real world data. Oh, and don't forget the $1500 tax credit for "Green" automobiles either! I've owned 2 of 'em... along with Hondas and Toyotas... when my Accord craps out... back to diesel. No doubt. Yes, you'll have to buy the DEF liquid (you can buy it @ wal-mart), but hey, where else can you buy a nice car that gets as much as 49-50 mpg while lugging along at under 2,000 rpm's?
Oh, and if you really want to have a VW TDI make some "performance"... just get bigger fuel nozzles, adjust the timing, and of course, install a bigger air intake. BUT... your car will lose fuel economy, and you take a huge risk on wear and tear on your engine, transmission, etc.
Overall, the TDI is a great car, is fun, and of course... built in the USA (Yes, Chattanooga, TN to be exact).
You'll be miles and $$$ ahead in a TDI. Why else is there a 6 month delay in production boys? DEMAND.