two smaller subcompact models, the amc eagle kammback, based on the amc spirit sedan (née gremlin), and the sporty eagle sx/4, based on the spirit liftback, debuted as "eagle series 50" models. the kammback and sx/4 came standard with gm's "iron duke" four-cylinder engine, four-speed manual transmission, and power steering. the series 50 eagles reflected the styling updates that the larger series 30 models showed for 1981. the sx/4 model was available with a sport package, as well. "billed as 'the sports car that doesn't always need a road' the sx/4 two-door hatchback had a sporty look, but hardly qualified as a sports car."