AMC:
Actually, AMC was on the verge of shaking up its car line. Their answer to the Mustang, the Javelin, debuted in '68. Standard air-conditioning was a '67 introduction on Ambassadors (not even Cadillac had standard air back then). The Marlin, formerly a laughingstock, got a '67 restyle that actually made it a good-looking car. Interiors were vastly upgraded on upper-series models, though the AMC tradition of near-Soviet BOL interiors continued. The entire range of models got restyled in '68 to bring them much closer to Big Three styling trends - no more loopy AMC styling, at least for the moment (it would return with a vengeance in the '70s).
Sadly, it wasn't enough. I've owned four AMC products in my time, and all of them were very good cars, except my first of two Pacers, which had been vilely abused before I bought it. But the Big Three had the advertising bucks, and the resale value, and already, the handwriting was on the wall. Too bad - if there were still AMC's, I'd buy one.