CAFE standards were written in such a way as to encourage large vehicle footprints to work around the requirements of the standards. Motorcycling youtuber fortnine offers a good view on some other aspects of the situation. https://www.youtube.com/watch?v=YpuX-5E7xoU
In other words, this problem was caused by a progressive regulation intended to help the environment that had the exact opposite effect intended. They set aggressive targets for MPG that were not able to be reached and still produce a car that people want to drive. Remember the tiny Ford Ranger or Chevy S10? If they were produced today, they would be expected to have a very high MPG, which would require an engine uns…
It was caused by the legislature undermining progressive regulation. Congress was the one that required the EPA to establish different standards for “non-passenger automobiles” and allow SUVs to classify as light trucks.
It’s the only thing that saved the American car companies from bankruptcy post oil embargo shakeup so now its too entrenched a policy to remove.