Cadillac Eldorado Gen 6

Introduction

For 1979, a new, trimmer Eldorado was introduced, and for the first time the car shared its chassis with the Buick Riviera as well as the Toronado. Smaller 350 and 368 in³ (5.7 and 6.0 litre) V8's replaced the 500 and 425 in³ (8.2 and 7.0 litre) of the preceding model, giving better fuel efficiency.

For 1979, it was offered only with the Oldsmobile 350 as standard, then in 1980 this was replaced with the Cadillac 368. For California only, the Olds 350 was retained for 1980. In both the 1980 Seville and Eldorado (which shared their frames), the 368s in 1980 came with DEFI, whereas for the larger RWD Cadillacs, the 368 only came with a 4-barrel Quadrjet carburettor.

Independent rear suspension was adopted, helping retain rear-seat and trunk room in the smaller body. The most notable styling touch was an extreme notchback roofline, making the rear window almost vertical. The Eldorado Biarritz model resurrected the stainless-steel roof concept from the first Brougham.

Although downsized, these Eldorados were still substantial-sized cars with good room and power. In 1984, Cadillac also introduced a convertible version of Eldorado Biarritz. It was 200 pounds (91 kg) heavier, but featured the same interior as other Biarritz versions. The model year of 1985 was the last year for the AMC, Inc. aftermarket conversion Eldorado convertible was ever produced. Because of its limited edition (around 3000 total), the convertible models are now highly sought after by numerous collectors.

Prior to the 'official' 1984 and 1985 Eldorado convertibles marketed by Cadillac, some 1979-83 Eldorados were made into convertibles by independent coachbuilders e.g. American Sunroof Corporation, Custom Coach (Lima, Ohio), Hess & Eisenhardt. The same coachbuilders also converted the Oldsmobile Toronado into a ragtop. Of all Eldorados, this generation can claim to be the best suited to the market and the times.

An unfortunate interlude occurred in 1981, when Cadillac offered three unpopular engines. The first was the V8-6-4 variable displacement engine, which was designed to deactivate some cylinders when full power was not needed, helping meet GM's obligations under the government fuel economy ("CAFE") standards. Unfortunately it did not work as planned, and sometimes did not work at all. It was a reduced bore version of the 1968 model-year 472, sharing that engine's stroke and also that of the model-year 1977–1979 425. The engine itself was extremely rugged and durable, but its complex electronics were the source of customer complaints. (note: the new small 1979 Eldorado did not use the 425, only the Oldsmobile-sourced 350).

Another problem with the 1981 model year was an unexplained balancing problem that affected the vehicle's overall handling. GM corrected this by installing a large, heavy metal plate under the driver's seat. This issue with the vehicle was brought to light in the 1995 movie Casino, where Robert DeNiro's character survives a bomb planted under the driver's seat of his Cadillac Eldorado, and the plate is credited with saving his life after the explosion. This was based on an actual incident that happened to Frank Rosenthal, upon whose life story the film was based.

Another disastrous engine option was the 350 in³ (5.7 litre) Oldsmobile Diesel V8, first offered in 1979. Designed as a specific block, rather than a sleeved gasoline conversion, the engine was plagued with problems: drivers were unfamiliar with diesel vehicles (e.g. not waiting for glow plug warmup), and the head bolts were inadequate for the 22:1 compression design, leading to frequent head gasket failures. Subsequent revisions to the block and heads improved things, and the engine was de-rated from 120 hp (89 kW) to 105 hp (78 kW) by 1981. The history of these multiple failures frequently resulted in dealer-provided gasoline-conversions of those vehicles, and the option was dropped by 1985.

The third engine, the HT-4100 was an in-house design that mated cast-iron heads to an aluminium block. Designed for a new generation of front-wheel drive vehicles, it was inadequate for a full-sized Cadillac, which weighed over 4000 pounds. HT-4100s failed in large numbers; thousands were replaced under warranty. Nevertheless, the Eldorado's reputation was not permanently hurt, and sales rose to unprecedented heights, nearly 100,000 units by 1984, an astonishing volume for one of the most expensive models available.