Maybe its 50 im thinking of? Its the long final drive thats makes the difference. Thats what I hear from TDI people anyway.... twin turbos..... are you going with smaller ones for faster spool up or bigger to try and run 50 psi or something?
Autoweek got 49.9 mpg with a bone stock TDI. The Prius did worse. Mostly highway driving, from Ann Arbor to Holland, MI and back. A chip should increase that, unless you drive like I do.