TDI 3.0 are awesome, but wait out till the diesel gate issue has been cleared for a fix. Depending on your location of residency, expect possible smog tesing for NO... I've had 3 TDI, and never had any major problem except major maintenance like timing belt. The plus side is fuel mileage, very good reliability, and the SUV have an outstanding drive train. Also, these vehicle (Toureg, Q7, and Porsche) use urea with every oil change.
Wait for the dealership offer substantial discount on the 2015 model, i've heard 15K off in San Antonio, Texas on a Q7. But not quite sure for the Porsche???
Best of Luck,