Time marches on

I'm grading practice exams today and I have the football games on TV for ambient noise. One car ad that has run several times features a child who wants her father to drop her off around the corner from school because the cool kids' families drive hybrids. Dad points out that the SUV they are sitting in is a hybrid. The voice-over then tells us that the model advertised has the best fuel economy of any SUV--34 miles per gallon.
Now, I know for a fact there were cars on the roads in the 1970s that got 40+ mpg running on gasoline alone. Granted, they weren't as big as this SUV, but back then no one would have believed that giant petroleum-powered cars would ever make a comeback unless someone figured out how to manufacture more petroleum. We figured it was just a matter of time, and not much time, before 50+ mpg was the norm, and only a little more time before petroleum-based fuel was replaced by something renewable and cleaner.
Yeah.