My big, heavy, 290 horsepower, double overhead cam, 32 valve V8, Lincoln Mark VIII gets 27 mpg at 75 mph, and it's ten years old. Progress seems to be very slow.
Except that something even heavier (the 300C SRT8) now gets 27 mpg with a *500* horsepower engine.
I have a 2006 Dodge 1500 truck with the MDS Hemi 5.7L with 345hp and it gets 28mpg at < 65mph on the highway. It kicks down to 4 cylinders when the power isn’t needed.