The Chevelle line, for 1966, consisted of the base level Chevelle 300, Chevelle 300 Deluxe, Chevelle Malibu, and Chevelle SS-396 series. The base-level Chevelle was available as a 2- and 4-door sedan. To help distinguish it from its upper-trim level siblings, it had very little ornamentation. There were fender series emblems, venti-pane frames, moldings around the windshield and rear window, four headlamps with anodized aluminum bezels, front bumper mounted park/turn lights, small hubcaps, and a single-unit rear light with built-in back-up lights. Other features included a rear cove Chevelle nameplate and grille outline moldings.

Chevrolet produced a total of 28,600 Chevelle 300s with the majority being fitted with six-cylinder engines. The six-cylinder powerplant was a 192 cubic-inch unit that offered 120 horsepower and features a Rochester one-barrel carburetor and hydraulic valve lifters. The overhead-valve V8 displaced 283 cubic-inches and offered nearly 200 horsepower. Just, 5,300 examples of the V8 were fitted into the engine bay of the Chevelle 300 Series. Pricing for the 4-door sedan began at $2,200 while the 2-door version was $2,175.

A Chevelle 300 Deluxe Series added full-length bodyside moldings, rear fender nameplates, and painted rear quarter reveal moldings. They also had tailgate molding and an emblem on the station wagon body styles. Inside, the 300 Deluxe had a dual-spoke steering wheel with a horn ring. They had a color-keyed upper instrument panel with a lower panel trim strip. The armrests in the rear seats had built-in ashtrays. The interiors were upholstered in cloth and vinyl.