A dramatically different front-drive, C-body Coupe DeVille (and Fleetwood sedan) hit the market late in March of 1984, as early '85 models. The Grand Old Caddies lost two feet in length and about 600 pounds. Their front-drive chassis layout was also used by Buick Electra and Oldsmobile Ninety-Eight. Though not exactly small, both were a far cry from the DeVilles and Fleetwoods of prior eras. Arriving in the fall was a new Fleetwood coupe, with formal cabriolet vinyl roof and opera lamps, as well as wire wheel covers. Both coupe and sedan carried a claimed six passengers.
A transverse-mounted 249 cu. in. (4.1 liter) V-8 engine with throttle-body fuel injection was standard; 4.3-liter V-6 diesel a no-charge option. Cadillac's was the only transverse-mounted V-8 available in the world. Oldsmobile's diesel V-8 engine also was available. Inside the automatic transmission, the torque converter clutch was computer-controlled and operated by silicone fluid.
All models included the Retained power Accessory System, which permitted use of power windows and trunk release for 10 minutes after shutting off the engine. A third brake light was now mounted on the rear panel shelf. Standard equipment included
| Model | Series Number | Body/Style Number | Body Type | Seating | Factory Price | Shipping Weight | Production Total |
| DeVille (V-8) | 6C | D47 | 2-door Coupe | 6 | $18,355 | 3330 lb | 37,485 (total includes the 2-door Fleetwood) |
| DeVille (V-8) | 6C | D69 | 4-door Sedan | 6 | $18,947 | 3327 lb | 114,278 (total included the 4-door Fleetwood) |
Engine note: Diesel V-6 engines were available on DeVille & Fleetwood models with no extra charge.
| Feature | BASE V-8 | OPTIONAL DIESEL V-6 |
| Type | 90-degree, overhead valve V-8. Cast iron block and head | 90-degree, overhead valve V-8. Cast iron block and head |
| Displacement | 249 cu. in. (4.1 liters | 262 cu. in. (4.3 liters |
| Bore & stroke | 3.47 x 3.31 in. | 4.06 x 3.39 in. |
| Compression ratio | 8.5:1 | 21.6:1 |
| Brake horsepower | 125 at 4200 R.P.M. | 85 at 3600 R.P.M. |
| Torque | 190 lbs.-ft. at 2200 R.P.M. | 165 lbs.-ft. at 1600 R.P.M. |
| Main bearings | Five | Four |
| Valve lifters | Hydraulic | Hydraulic |
| Fuel Supply | Fuel Injection | Fuel Injection |
| Wheelbase | 110.8 in. |
| Overall length | 195.0 in. |
| Height | 55.0 in. |
| Width | 71.7 in. |
| Front Tread | 60.3 in. |
| Rear Tread | 59.8 in. |
| Standard Tires | P205/75R14 SBR WSW |
| Transmission | Four-speed overdrive automatic (THM440-T4) standard on DeVille/Fleetwood |
| Gear ratio | (1st) 2.92:1; (2nd) 1.57:1; (3rd) 1.00:1; (4th) 0.67:1; (Rev) 2.38:1. |
| Standard final drive ratio | 2.97:1 except with diesel, 3.06:1 |
| Steering | rack-and-pinion |
| Front suspension | MacPherson struts, lower control arms, coil springs and stabilizer bar |
| Rear suspension | independent struts, coil springs, stabilizer bar, electronic level control |
| Brakes | front disc, rear drum |
| Disc dia. | 10.25 in. |
| Drum dia. | 8.9 in. |
| Fuel tank | 18.0 gal |
1984