Differing mainly in dimensions from DeVille and Fleetwood, carrying the new crosshatch grille, limos could not have the diesel engine option. Both standard and Formal Limousine models included a dual accessory panel so rear passengers could adjust the climate control and power windows. The formal edition held a sliding glass partition, with seating for seven. Standard limos held eight. Interiors came in dark blue Heather cloth, or black in the back. All carried two fold-down auxiliary seats.
| Model Number | Style Number | Body Type | Seating | Factory Price | Shipping Weight | Production Total |
| 6C | B47 | 2-door Coupe | 6 | $15,777 / 15,942 | 3854 / 4069 lb | 62,724 (total includes the 2-door DeVille) |
| 6C | B69 | 4-door Sedan | 6 | $16,190 / 16,355 | 3884 / 4115 lb | 86,991 (total included the 4-door DeVille) |
| 6D | F23 | 4-door Sedan | 8 | $24,464 | 4629 lb | 1,200 |
| 6D | F33 | 4-door Formal Limousine | 7 | $25,323 | 4717 lb | |
| 6D | Z90 | Commercial Chassis | N/A | N/A | N/A |
Figures before the slash are for V-6 engine, after slash for variable-displacement gas V8-6-4. A diesel V-8 was also available on DeVille/Brougham/Eldorado. By late spring 1981, prices rose on all except Eldorado: Seville reached $23,000 for the diesel, Coupe DeVille $14,345, Brougham sedan $17,420.
| Feature | Std. Brougham | Opt. Brougham & Std. Limousine | Commercial |
| Type | 90-degree, overhead valve V-6. Cast iron block and head | 90-degree, overhead valve V-8. Cast iron block and head | 90-degree, overhead valve variable-displacement. Cast iron block and head |
| Displacement | 252 cu. in. (4.1 liters) | 350 cu. in. (5.7 liters) | 368 cu. in. (6.0 liters) |
| Bore & stroke | 3.965 x 3.40 in. | 4.057 x 3.385 in. | 3.80 x 4.06 in. |
| Compression ratio | 8.0:1 | 22.5:1 | 8.2:1 |
| Brake horsepower | 125 at 3800 R.P.M. | 105 at 3200 R.P.M. | 150 at 3800 R.P.M. |
| Torque | 210 lbs.-ft. at 2000 R.P.M. | 200 lbs.-ft. at 1600 R.P.M. | 265 lbs.-ft. at 1600 R.P.M. |
| Main bearings | Four | Five | Five |
| Valve lifters | Hydraulic | Hydraulic | Hydraulic |
| Fuel supply | 4-bbl. carburetor | Fuel injection | 4-bbl carburetor |
| Manufacturer | Buick | Oldsmobile | - |
| VIN code | 4 | N | 6 |
| Wheelbase | 121.4 in. |
| Overall length | 221.0 in. |
| Height | 56.7 in. |
| Width | 76.5 in. max. |
| Front Tread | 61.7 in. |
| Rear Tread | 60.7 in. |
| Standard Tires | P215/75R15 SBR wide WSW |
| Transmission | Turbo Hydra-matic transmission, column shift. |
| Gear ratios for Brougham & limo V8-368 | (1st) 2.48:1; (2nd) 1.48:1; (3rd) 1.00:1; (Rev) 2.07:1 |
| Other three-speed models | (1st) 2.74:1; (2nd) 1.57:1; (3rd) 1.00:1; (Rev) 2.07:1. |
| Four-speed automatic in Brougham w/V-6 | (1st) 2.74:1; (2nd) 1.57:1; (3rd) 1.00:1: (4th) 0.667:1; (Rev) 2.07:1 |
| Standard final drive ratio | (Brougham) 2.41:1 except w/V-6, 3.23:1; (limos) 3.08:1 |
| Steering | recirculating ball (power assisted |
| Suspension | same as 1980. |
| Brakes | front disc, rear drum |
| Fuel tank | (Brougham) 24.6 gal. exc. diesel, 27 gal. and V-6, 25 gal.; (limos) 24.6 gal. |
1980