I understand what your saying & agree with it to a degree. At the same time, I think auto makers are incredibly lazy when it comes to MPG. I would rather have better MPG in whatever vehicle I'm in, be it a big truck or a little compact car. I find it ridiculous that the best gas mileage of any car I've ever had was a 10 year old VW jetta I got right out of High school. I got consistently 35-45 MPG. A brand new VW Jetta now gets 30-38. That's not progress & its not good for consumers. And the $ you pay for one has gone up substantially. And crediting Trump with getting your vehicles for cheaper is absurd as well. The steel tarrifs he's put in place are going to drive up the cost of vehicles at least as much as would be added by increasing MPG.
The reason you have not seen mpg increases is also because of the government... They have been increasing the amount of safety equipment required in vehicles for decades. This adds weight, weight kills economy.
One example is diesels. The reason they do not make the same or better mpg today than pre 2007 is because of the epa. Those clowns decided diesels should not smoke anymore. In creating the emissions control systems to eliminate the smoke they increased fuel consumption, weight due to complex systems needed to control soot and complexity that has also killed diesels long held lifespan advantage over gas powered vehicles.
In the same way we have given up reliability in sleds due to the epa mandating stupid restrictions on manufacturers. They will tell you these were improvements and the improvements are currently saving the world but anybody with a functional brain knows this is a lie. Once again, "we the people" pay the price in so many ways for the stupidity of our government officials.
In the case of VW, the government sued them and won. VW was just trying to give you power, economy and longevity... To do it they had to break the rules, and they were caught. People jumped on the bandwagon under the impression that what VW did was going to pollute the world, another stupid big government lie...