Claim could be true, or at least close. I owned a '72 diesel Rabbit that got 50mpg on the hwy. That was back in the mid 70's when VW had dirty diesel engines and all that was available at the pumps was the high sulpher stuff.
That was clever, since they didn't start production of the Golf until '74, intro'd it in the US in '75 and didn't call it the Rabbit until '78, which is when the diesel engines started to come along...
I remember The RoadWarrior..To understand who he was, you have to go back to another time..the world was powered by the black fuel & the desert sprouted great cities..Gone now, swept away..two mighty warrior tribes went to war & touched off a blaze which engulfed them all. Without fuel, they were nothing..thundering machines sputtered & stopped..Only those mobile enough to scavenge, brutal enough to pillage would survive. The gangs took over the highways, ready to wage war for a tank of juice