As someone who regularly gets 55+ mpg on his Prius, I say this case is utter BS. I drive 100 miles round trip to work each day, mostly highway between Fort Worth and North Dallas. People in Dallas will not let you go 50 mph on the highway. My speed varies between 60 ~ 70 mph depending on traffic conditions. Sure, I get a little less mileage at 70, but so does everyone else on that road. And it's not like it requires some kind of advanced certification to get that mileage. I traded my 3/4 Chevy Duramax w/300+ hp and 500+ lbs of torque in on the Prius. My first tank, I got 52mpg.
Next thing you know, people will sue Remington since their gun won't hit the target, Fender since their guitar doesn't sound like David Gilmour, and Louisville Slugger because their bat doesn't hit home runs.