I think we can all agree that the ever increasing EPA regulations of the 1970's ended the muscle car era. Rapidly followed by the
oil embargo, those two events pretty much ended the big blocks in cars, and brought back 4 cylinders and likely spawned the V6. Decades of cars that ran like crap, and engines that continued run with the key off (dieseling), followed.
50 yrs later and we now have cars that run almost perfectly with warranties that last longer than some cars in the 1960's. Safe cars with comforts everywhere. They even come with GPS systems that will guide you to a one lane dirt road in a national forest from West Virginia to Yellow Stone. Muscle cars now surpass any measure of performance you want to compare to the 60's, and yet we complain. No wonder things keep getting better. We are never happy with how good we have it. I guess that is a good thing. LOL