Ah yes, those wildly innovative do-gooder car companies of the 50s:

"The “smog conspiracy” was revealed in 1968 when the US Department of Justice filed an anti-trust case against the Big Three. They were accused of colluding to withhold the installation of catalytic converters and other technologies to reduce pollution. “Beginning at least as early as 1953, and continuing thereafter,” alleged the Department of Justice, “the defendants and co-conspirators have been engaged in a combination and conspiracy in unreasonable restraint of the aforesaid interstate trade and commerce in motor vehicle air pollution control equipment.”

https://www.counterpunch.org/2015/10/28/automakers-and-their...