Dad got 55 or so miles to the gallon out of his diesels.
The TDI I don’t recall, but it was significantly less after it ate the deer.
He still mentions the diesel Rabbit he had with a bit of a sigh once in awhile.
Looking into my old log book for the ‘96 Jetta, I got the highest running pure highway @28MPG, the average was about 22.
Except for the day spent doing nothing but city driving, that was around 12 or 14.
My 2007 GMC 1500 does about that. It seems to me that the new EPA gas has less btu equivalent than it used to especially with alcohol in it. Wonder what some of these new vehicles would do with some good ole leaded gas.