The new ones don't get 42 though. I couldn't Even get that low in mine.
In fact, the lifetime averages in mine, were very close. Same commute, same driving.
MK4 TDI - 48mpg lifetime
MK5 BRM TDI - 46 MPG lifetime
MK6 TDI - 47 MPG lifetime.
Yes the Mk4 could get the best mileage when pushed...