I own an 2008 Prius. ALL of my driving is country highway and at ~58 mph (90 km/h - keeps me from getting a ticket)I get 54 mpg. If I instead kept it to 85 km/h I'd get about 56 mpg.
I have no idea who these people are you refer to, but they're
1) not driving their cars very well (i.e. high acceleration) or,
2) their tires are flat or,
3) they are in desperate need of a tune-up.
Lastly, I HATE it when people say stuff like 'my 197X Continental/Pinto/Thunderbird got 9 bajillion mpg and that was back then'. You know what, yeah, the VW you refer to gets decent mileage at highways speeds only. A hybrid gets good (only, if you consider 50mpg good) mileage under city AND highway speeds.