Again, Im not speaking about WHY the government mandated the change. Im speaking strictly about the fact that in the 70s, the government went ahead and mandated big, big changes in both emissions standards and fuel efficiency. Then threw in the double whammy of changing the laws regarding fuel. Radical change was mandated by the government with very much of a "Do it or Else" mentality. And thats something you wont see today. Sure...small changes in efficiency standards and what not will take place. But not like what was seen back in the 70s....the unions, oil companies and auto manufactureres wont allow it. THEY run the show now.
As far as the fuel thing goes, correct me if Im wrong, you obviously know more than me on the subject, but octane levels after the removal of tetraethyl lead didnt come back UP until several years later, no?