VI. (Miss) Engineering Disasters: Diesel and V8-6-4
As the 1970s drew to a close, Cadillac worked to adapt to shifting consumer expectations and mounting regulatory demands. Some of its efforts—like the successful downsizing of its largest sedans—were well-executed and well-received. Others, particularly its powertrain decisions, proved more damaging. This period became a defining chapter in Cadillac’s gradual erosion of mechanical prestige.
In 1978, Cadillac began offering a diesel engine option—first in the Seville, then across the DeVille and Eldorado lines. Sourced from Oldsmobile, the 350 cu in. (5.7-liter) V8 diesel promised significantly improved fuel economy, touting up to 30% better mileage than its gasoline counterpart. On paper, it answered the fuel crisis. In practice, it fell apart—literally. Output was an anemic 120 horsepower, with 0–60 times often exceeding 15 seconds.
Performance was sluggish. Worse, reliability quickly cratered. Chronic issues included head gasket failures, cracked engine blocks, and malfunctioning injector pumps. Cadillac customers, long accustomed to quiet, dependable drivetrains, balked at the noisy operation, rough starts, and expensive repairs. Within a few years, the diesel V8 had earned a place among the industry’s most notorious engineering flops. Its damage to Cadillac’s reputation for durability was severe and lasting.
The 1979 Eldorado marked a major shift. Downsized alongside its Riviera and Toronado siblings, the new Eldorado migrated to GM’s E-body front-wheel-drive platform. The result: a car nearly 20 inches shorter and roughly 1,200 pounds lighter than its predecessor, yet with comparable interior space thanks to more efficient packaging.
Styling, under Wayne Kady, leaned into neoclassical flourishes, but under the hood, the Eldorado fell short. Engine options included the Oldsmobile-sourced 350 cu in. gasoline V8 and the problematic diesel. The gasoline engine, choked by emissions equipment, delivered around 170 horsepower—adequate, but far from inspiring.
The second-generation Seville arrived in 1980, wearing one of the most divisive designs in Cadillac history. Its “bustle-back” trunk, a nod to 1930s English coachwork and contemporary Rolls-Royce sedans, polarized opinion. But it succeeded in making the Seville instantly recognizable. Lincoln took notice and borrowed the concept for its 1982 Continental.
Like the new Eldorado, the Seville now rode on the E-body platform and shared its engine options. Reviews praised the Seville’s distinctive styling and smooth ride, but persistent dissatisfaction with the diesel V8 and underwhelming acceleration muted broader enthusiasm.
In 1981, Cadillac responded to intensifying fuel economy pressure with an ambitious—but flawed—technological gambit: the V8-6-4 engine. Designed in collaboration with Motorola, the 368 cu in. (6.0-liter) V8 used early electronic controls to deactivate two or four cylinders under light load. It could theoretically switch between running on eight, six, or four cylinders—decades before similar systems would succeed.
But the electronics weren’t ready. Transition between cylinder modes was clumsy. Owners reported hesitation, surging, rough idle, and general drivability issues. Dealerships, inundated with complaints, frequently disabled the system altogether. After a single model year, the V8-6-4 was quietly dropped from the retail lineup, surviving briefly in fleet and limousine use. Despite its forward-thinking premise, it became another cautionary tale—ambition outpacing execution.
Cadillac’s appetite for technology didn’t stop there. In parallel, it pushed aggressively into electronic instrumentation and climate systems. Digital dashboards, trip computers, and automatic climate controls became increasingly common. These features looked futuristic in the showroom, but early adopters often faced glitches, failures, and unintuitive interfaces. What was meant to be sophistication began to feel like overcomplication.
This period revealed a tension Cadillac would struggle with for decades: the need to modernize without betraying its core identity. The 1977 full-size sedan downsizing had been a triumph, and the second-generation Seville’s design struck a cultural chord. But these wins were increasingly overshadowed by high-profile misfires—particularly the diesel and the V8-6-4. By the early 1980s, Cadillac’s prestige still carried weight. But its reliability narrative was cracking. Once the “Standard of the World,” Cadillac now found itself navigating a world that demanded smaller engines, tighter tolerances, and fewer excuses.