I imagine that currently the economy stat is based off of the car going at it’s most efficient speed, whether it be 5mph or 100mph. Sorry if I’m wrong. But if that’s true, then it would be hard to understand what the economy stat means in relation to reality since car manufacturers don’t advertise that. They advertise an economy rating comprised of tests for city and highway driving. For instance, my 2012 Mazda 3 can cruise at 35mph at 70mpg, but Mazda doesn’t advertise that. They said that it does 28mpg city and 40mpg hwy.
Sorry if I’m a big dummy and the economy stat is calculated some other way that represents realistic economy ratings; maybe such as a combined fuel economy.