In 1965 the Buick Riviera received minor styling changes that consisted of headlights that were now stacked in front of the fenders and covered with clam shell looking covers when not in use, as well as the taillights that were now stretched almost the entire width of the car. However the big news for the '65 Riviera was the addition of the Gran Sport (GS) option that included the 425 Super Wildcat V8, 360 hp engine with dual 4 -barrel carburetors and a Posi-Traction rear end with 3.58:1 gearing. Top speed was estimated at 125 mph.