The muscle car era ended not with a bang but with a series of incremental retreats. The 1971 compression ratio reductions. The 1972 switch to net horsepower ratings that made the same engines look weaker on paper. The 1973 bumper regulations that added weight. The 1974 fuel crisis that made big-block cars difficult to justify.

By 1975, the engines that had defined the era were gone or severely detuned. The 454 that had made 450 horsepower in 1970 was making 215 horsepower by 1975 — and that was the honest net figure, not the optimistic gross figure the earlier cars had used.

The cars from 1966-1971 represent the pure expression of the era. The window is specific. The cars that matter are from that window. Everything else is either prologue or epilogue.