The Buick Riviera received its first major redesign in 1966, sharing the new E-Body with the Oldsmobile Toronado and upcoming 1967 Cadillac Eldorado. However, the latter two were front-wheel drive while the Riviera maintained its traditional front-engine rear-wheel drive.

Sharp fender lines carried through to the rear of the car, kicking up over the rear fenders and copying the front edges at the rear. Brightwork was almost non-existent, and taillights were recessed. The vent windows were removed, while the interior was widened 2.2 inches for three abreast seating. The front seat was a split bench, but high-back Strato buckets were optional. A new dash was fully instrumented with a strange rotating drum speedometer in the center, which was quite legible until the cable wore.

Power steering and brakes were standardized, with front disc brakes optional, but air conditioning was an optional extra. Base engine was the 340 bhp 425 cid V-8, while the Gran Sport option continued to be offered for $450 and included bucket seats, heavy duty suspension, a limited-slip rear axle, ribbed alloy rocker covers, chrome air cleaner and GS lettering on the fenders. A dealer-installed 360 bhp, 425 cubic-inch Super Wildcat package was offered which included dual 4-barrel Carter carburetors and returned 0-60 in 7.7 seconds and a quarter-mile in 15.9 seconds at 87 mph.

Riviera sales jumped to 45,348 units from 34,586 and 5,718 of those were the Gran Sport model. Of the GS sales only 179 cars were fitted with the 360 bhp Super Wildcat engine. Other Rivera options included power windows, four- and six-way power seats, tilt steering column, tinted glass, cruise control, cornering lights, wire wheel covers, 5-spoke chrome wheels and an automatic trunk release.

Standard Riviera equipment included the 3-speed Super Turbine transmission, power steering, power brakes, two-speed electric wipers with washers, safety buzzers and warning lights, tilt steering wheel, upper and lower dash safety pads, console gear selector, walnut paneling on the dash and full carpeting. Carpeted lower door panels were an option.