Wow.. that's really shocking. 30MPG in a 2006? It has to be a DSG....
I have a 2006 Manual. I've been toying with selling it and have had a few DSG owners call me and say I was lying on the 49MPG advertised. I'm not. I hve at least 6 trips -- including Austin, TX to Raleigh, NC and back -- where it achieved 730 to 760 miles on a single tank of fuel. I drive 3 to 4 times per year 732 miles door to door to my parents in Memphis, TN from Raleigh... on a single tank... actually I tend to have fuel to spare. The System reads 0 miles left, but I get 50 to 100 miles (depending on highway or city) after it says I'm totally out of fuel on the display (not all TDIs have this, it's akin to the EVIC system).
I know a guy with a no-sunroof 2006 DSG who gets about 48mpg higwhay and 40-41 in city. I average 40 to 42 city. He says he never gets less than 625 to the light, and on a normal week of driving for me the light comes on around 490-505 miles.... still not bad for something that takes a little over 15 gallons if you run it dry (which I did coming back from texas... hence how I know I can go 100 miles beyond that 0 mile notice, on pure biodiesel no less, which supposedly has a lower BTU content and thus reduced mileage).
Anyone with a TDI that isn't seeing a minimum of 42 combined... you might wanna change your filters and have the car checked out. That's just not normal. I have 52,000 on mine... I was seeing this economy at least at 30k miles...
Anything under 30k is likely not broken in. Go get it up to 90 on the highway a few times and change the oil.
If you compare a 2006 Jetta TDI and a 2006 Prius the Prius for $2k less has a lot less options: heated seats, sunroof, the first two that come to mind. I enjoy and use those two items a lot with my car, and that was one of the deciding factors in keeping it. My back isn't that great anymore, starts of fusion in the lower end due to a rear end about 10 years ago. The old mercedes is economical (84 190D) but the seats kill me. I'd rather stay under a note for a car and reduce the doctor and chiropractor bills than spend a few thousand on my back to save a few bucks on transportation...
Anyway, I love all diesels equal. I was worried about our CRD at first but he's turned out to be a good lil Jeep. Those with modern TDIs... you should be checking into whats going on. Now I will say, I shift at 2200rpm in city, always. I never have the car over 2200rpm for basically any reason other than to tick off a Nissan owner or to charge past a Prius up one of our many hills. Agressive driving I will get 38-40, driving it conservative (and with the 240ft lb torque my modifeid TDI is making to the wheels even a 2200rpm shift gets the car flying up on the bumper of whatever is in front of you) gets me the more pre-2005.5 economy of 42 city and 49 highway.
Also, take out the spare tire. That saves on weight. Do a mufflerectomy - basically just cut the darn thing out. That saves a hundred pounds right there, and opens it up a lot.
I've not modified the muffler, but I'm going to do that likely this weekend.
OH and manual owner... spend the $$ for a Valeo clutch kit. The Sachs kit with Dual mass flywheel is a POS, mine died at 30k miles... no warranty coverage (there is a TSB out for this now). The Single Mass FLywheel is easier to engage and it has given me about a 6% increase in city economy (highway didn't seem to change too much).