Standard engine for DeVille and Fleetwood Brougham was the "modulated displacement" 368 cu. in. (6.0-liter) V8-6-4, with digital fuel injection. Optional: a 252 cu. in. (4.1-liter) V-6, provided by Buick. That V-6 had Computer Command Control and a knock sensor to adjust spark advance, as well as diagnostics. The Olds diesel V-8 was also offered.
Externally, DeVilles and Fleetwoods carried a new forward-peaked grille with heavy wide upper header bar (Cadillac script again at the side) over an undivided tight crosshatch pattern. Quad headlamps sat above quad amber parking/signal lamps, with wraparound clear/amber cornering lights. Standard wheel covers displayed a Cadillac crest on dark red background. New standard Electronic Climate Control offered digital accuracy. Standard equipment also included a six-way power passenger seat, power windows, and low-fuel warning. New pillow-style seating came in rich Heather cloth (four colors); or leather in ribbed seating areas (ten colors). Sedan DeVilles could have automatic lap-shoulder belt for driver and front passenger. Other options: a Heavy-Duty Ride package, wire wheel covers, and Elk Grain vinyl roof.
| Model Number | Style Number | Body Type | Seating | Factory Price | Shipping Weight | Production Total |
| 6C | D47 | 2-door Coupe | 6 | $13,285 / 13,450 | 3801 / 4016 lb | 62,724 (total includes the 2-door Fleetwood Brougham) |
| 6C | D69 | 4-door Sedan | 6 | $13,682 / 13,847 | 3852 / 4067 lb | 86,991 (total included the 4-door Fleetwood Brougham) |
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. By late spring 1981, prices rose on all reached $23,000 for the diesel, Coupe DeVille $14,345.
| Feature | V-6 | Diesel V-8 |
| Type | 90-degree, overhead valve V-6. Cast iron block and head | 90-degree, overhead valve V-8. Cast iron block and head |
| Displacement | 252 cu. in. (4.1 liters) | 350 cu. in. (5.7 liters) |
| Bore & stroke | 3.965 x 3.40 in. | 4.057 x 3.385 in. |
| Compression ratio | 8.0:1 | 22.5:1 |
| Brake horsepower | 125 @ 3800 rpm | 105 @ 3200 rpm |
| Torque | 210 lbs.-ft. @ 2000 rpm | 200 lbs.-ft. @ 1600 rpm |
| Main Bearings | Four | |
| Valve Lifters | Hydraulic | |
| Fuel Supply | 4-bbl. Carburetor | |
| Made by | Buick | Oldsmobile |
| VIN Code | 4 | N |
| Wheelbase | 121.4 in. |
| Overall length | 221.0 in. |
| Height | DeVille Coupe 54.6 in.; DeVille sedan 55.6 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 standard on all models; column shift. |
| Gear ratios 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 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 | 2.41:1 except w/V-6, 3.23:1 |
| Steering | recirculating ball (power assisted |
| Front suspension | coil springs and link-type stabilizer bar. |
| Rear suspension | four-link drive coil springs, electronic level control available |
| Brakes | front disc, rear drum |
| Fuel tank | 24.6 gal. exc. diesel, 27 gal. and V-6, 25 gal. |
1980