You guys need to remember that the factory quoted Mpg can only be achieved on standard 16" alloys and that most cars will have larger wheels with stickier rubber and the average Mpg will be much lower ! That's the trade off for looking good ! Also driving style makes big difference- smooth acceleration with loads of coasting in gear will return higher Mpg than a car sitting in traffic or with duff thermostats !
Point is that the v6 tdi is not as thirsty engine as some might believe and from a driveability point of view i will choose a larger displacement engine all the time especially if you do long trips on motorways ! Enjoy your cars and be happy with the choice you have, i know i am ! Cheers !