Here's a quiz. Which saves more gas: trading in a 16-mile-a-gallon gas guzzler for a slightly more efficient car that gets 20 mpg? Or going from a gas-sipping sedan of 34-mpg to a hybrid that gets 50 mpg?
If you guessed the second choice, you're wrong.
Even a small improvement in gas guzzlers saves more gas than a big improvement in cars that already save. But cars aren't advertised that way in the U.S.
If they were rated in gallons per mile instead of the other way around, people might get a better idea of how to save gas.