The 1991 Buick Regal coupes were designed to a length of 191.6 inches and a height of 53 inches. The sedans came to 194.6 inches in length and 54.5 inches in height. All Buick Regals produced in this year have the same 72.5-inch width and 107.5-inch wheelbase.
The Custom coupe, Custom sedan, Limited coupe and Limited sedan Buick Regals all featured a 3.1-liter, 140-horsepower, V-6 engine. The Gran Sport coupe and Gran Sport sedan models of the 1991 Buick Regal were fitted with 3.8-liter, 170-horsepower, V-6 engines. All Buick Regals manufactured in this year featured four-speed, automatic transmissions.
Buick Regals fitted with the 3.1-liter engine offer an estimated 19 (city) miles per gallon of fuel and around 30 (highway) miles per gallon. The 3.8-liter engine performed roughly the same, offering 19 city miles and 28 highway miles per gallon. All Buick Regals produced in 1991 featured 16.5-gallon fuel tanks.