There's some merit to it. As all the cheap tricks have been done, belly pans, scoops, splitters, air dams, etc.
To move the bar up another 2MPG and beyond is going to be expensive.
Hell look were were are now with the cost of a truck today compared to 10 years ago. $7k difference easy, now a good portion of this inflation, but the fact remains to the extra increase it will be costly.
Government is pushing an agenda the business side doesn't want, cause its putting high margin vehicles out of the range of today's median incomes. Consumer lose, business loses, government? Well that's government, they know better what you need than you do. They don't care what it costs as that's evident in their everyday practice.