1975 Buick Riviera Limited, 455-4 V8, Automatic Transmission, Power Steering, Power Brakes, Factory Air Conditioning, Power Windows, Tilt Wheel, Cruise Control, Vinyl Landau Top, Little was changed for the 1975 Riviera. Most noticeable on the exterior is the redesigned grill treatment with rectangular headlights. Overall length was reduced by three and one-half inches, along with a 33-pound reduction in weight. Although the GS ride and handling package remained, lost was the Stage1 performance option. The only available engine for 1975 was the standard 205 horsepower 455, equipped with a catalytic converter.

Production again dropped to a new low. Only 17,036 Rivieras were built, including 3101 GS models. Radial tires were now standard along with power windows. Also, for the first time, electronic ignition was installed in the Riviera. Luxury was on the rise, as the convenience options increased over the previous year. 92.8% of the 1975 Rivieras had power seats, up from 89.9% in 1974. Cruise control was installed in 72.8% of those cars, compared to 60.7% in 1974. Other popular upgrades included air conditioning, which now was installed in 99.5% of the cars; 49.1% had 8-track tape decks, and 75% of the new models had vinyl tops. The GS package was only a scant $73 option. Still, the car did not sell well, and this is evident in the lack of road test information for the 1975 model done by magazines. Though it did not draw buyers to the showroom, the 1975 Riviera was a magnificent automobile. It may have strayed from the original concept, but the ride and the handling of a car of its size was very impressive. Interior appointments were plush and spacious. It was a leader in its class.
Although carrying over the same platform, mechanicals, and some body panels seen on the "Third Generation" Riviera, Buick replaced its distinctive 'boat tail' roofline with a more conventional-looking "Colonnade" treatment which was more in line with its LeSabre and Electra brethren than its front-wheel drive cousins. This turned the car from a hardtop coupe into a pillared coupe, as it featured wide B pillars and fixed quarter opera windows. A landau half-vinyl roof option was available. The car did retain its forward-jutting grille, albeit in a slightly modified form. Thus modified, the car looked far less distinctive than its predecessors, and even its platform mates, the Oldsmobile Toronado and Cadillac eldorado.

The Riviera was no lighter, and its standard 455 V8 lost more power, dropping to 230 hp (172 kW) and 245 hp (183 kW) for standard and Stage One models respectively. Max Trac was dropped from the option list after 1974 due to a lack of buyer interest. The revised styling did not improve sales, which fell to 20,129 in 1974, although it is impossible to determine how much this was a result of the energy crisis and how much was due to the tame appearance.[36] This generation introduced a novelty that later became federally mandated in a modified form, two high-mounted taillights above the trunk and below the rear window, which was shared on its platform twin the Toronado.

For 1975, the Riviera received an updated front fascia, which lost its forward-jutting theme through the redesign of the fiberglass front end cap. Quad rectangular headlights were mounted horizontally. The new vertical-bar grille echoed the "stand-up" theme that many GM cars of the day incorporated. Parking lights wrapped around the fender sides. The Stage One performance package was dropped for 1975, though the Gran Sport handling package would continue to be offered. The standard engine's output dipped to 205 hp (153 kW). Sales for 1975 were 17,306.

Minor changes greeted 1976 models, the most notable of which was a new crosshatch grille insert. The Gran Sport handling package was replaced by an 'S/R' package that had similar sporting pretensions. Sales rallied slightly to 20,082 for 1976.[37] ***ASK about our Extended Warranties Available For An Addit