Sadly I can't say that the 60s/70s had the best cars. There were a handful that stuck out, but, frankly, the Golden Era of automobiles is relative. In a sense, since they're only been around for just over a century, there haven't been enough changes to truly make any decade the 'Golden Era'.
If anything we're on the verge of a Golden Era as we step into alternate fuels, lower CO2 emissions, better collision safety and even cars that park themselves and incorporate adaptive cruise control right up to stopping themselves at traffic lights.
Technologically speaking vehicles are about to step into an era of automation, function leading form and a sensibility of purpose that before was more of a luxury than a necessity.
That being said, I do like progressive design. As far as aesthetics are concerned the latest breed of concepts and hybrids are always going to be, to me, and in relative terms, the peak of the Golden Era.
Also, the 50s because of the DB5 ^_^;
Not including that stupid GM Onstar system...