Economy
No, it is to deliver a product with more power for about the same price, which customers want more than the fuel economy.
Naturally, the leftists itch to pull that ever-present gun out of their pants to enforce a better and wiser course of action on these benighted consumers. How dare they make the wrong decision!
When gas prices go up, the decisions will start going the other way, same as they did before. The market always works.
It's worth noting that an average SUV today gets almost as good a mileage as a VW Beetle got back in the early 1970s, and they run a lot cleaner. There has been a lot of progress, and not all of it forced.