Chevrolet Camaro Z/28 Second Generation
The 1970s were a tough time for automakers, especially domestic ones. The Camaro and the Firebird models were both vastly underpowered compared to the outgoing models and the cars suffered because of it. The new emissions and fuel regulations were harsh and therefore limited the cars significantly. The Camaro Z/28 was a success for GM, but the second generation of the car fell short due to the times (via Classic Car).
The problem with all the new EPA regulations was that automakers were not able to adapt that quickly. Thus, most muscle cars from the 1970s were underpowered and sluggish compared to the previous generation. The second generation of the Camaro was often referred to as the least popular generation of the pony car as a result.