When I was pondering what to have i got quotes for identically spec'd 2.0TFSI and 3.0TDI Sline Plus vehicles.
Taking into account the price differential of the two vehicles and a very conservative fuel economy guess (25 mpg for the petrol and 34 for the diesel) @ 18,000 miles a year and the differences in petrol and diesel prices you would actually have to run the diesel into it's 4th year to make a saving over the petrol car.
So ordered a SQ5....perverse logic I know!