2004/5 TDI manual trans VW Jetta Station Wagons were rated at 47 Highway. They achieve >50mpg if driven lightly. Go like stink uphill in the mountains. No need to downshift on the highway to move through traffic.
Expensive to maintain though.
Just drove my 1999 Jetta TDI From Cushing, Oklahoma to Austin, Texas and back. 48.3 down to Austin and 48.1 on the way back. Used the A/C and ran along at 70mph the whole way.
It has 168,000 flawless miles on it. (Needs new rotors on the front brakes, though and the headlight lens have gone a bit cloudy.)
Oldplayer