By 1966 the Impala SS was beginning to lose its luster. The Caprice became the new top of the line Chevrolet stealing the Impala's luxury image while the SS was becoming more of an appearance package rather than a performance one. (Impala SS engine options included the 250ci 155hp I-6 283ci 195hp V-8 283ci 4 bbl 220hp V-8 327ci 4 bbl 275hp V-8 396ci 4 bbl 325 V-8 427ci 4 bbl 390hp V-8 and the 427ci 4 bbl 425hp V-8.) The Impala also lost its signature six round taillights which had been an Impala trademark since 1958. New large rectangular ones replaced them along with a more massively styled front end. The Mark IV 396 continued but a larger 427 version was introduced. It was rated at 390 bhp while the "special performance" version was rated at 425 bhp due to solid lifters four-barrel carb with aluminum manifold and heavy duty four bolt main block. The 427 was available with a special performance extra rugged extra noisy four speed manual transmission called the "rock-crusher." The Impala SS sales were down by more than 50% to 119312 due to lost sales to the Caprice and smaller midsize performance muscle cars. Prices ranged from $2684-$3199. Weights were approximately 3430-4005 lbs.
