I have a favorite late night road trip loop that I like to do. I've done it with ALL my vehicles, multiple times. Cars, trucks and motorcycles. It's exactly 100 miles. It involves some 60 to 65 mph two-lane, several miles through a small town with some stoplights, a fun blast up a mountain two-lane and then descending the winding road down the other side, a 35 mile up-and-down but largely straight two-land, and finally a 20 mile blast on 80 mph interstate.
Sometimes I do it for fun. Other times for fuel economy. So I can compare and contrast.
My Evil Beetle never did better than 47 mpg on the loop. My 2015 Passat (DSG + Phase One reprogramming) did an astounding 55 mpg.
At 80 mph, dead level and zero wind, the instantaneous fuel economy reading hovers around 45 mpg.
I consider that more than adequate. Zero complaints here.
p.s. When I hit a jackrabbit with the Evil Beetle on that loop the result was $800 in damage. I hit TWO of the little buggers with the Passat and didn't hurt the car a bit. Killed the bunnies deader then hell, though. So....WINNING.