Throughout the beginning and mid-20th century, Cadillac was known as "The Standard of the World." The GM subsidiary was known as the pinnacle of automotive engineering, and its cars were known to be better-built than many other brands, regardless of price point. However, things started to fall apart in the mid-1970s, when consumer interests began to shift away from large American luxury into a more European-style of luxury.During Cadillac's heyday, it offered a certain trim level that was, largely, more opulent than all the rest: the Biarritz. It was only offered on the Eldorado, one of the brand's most iconic nameplates. It quickly became an extremely popular option package following its introduction in the mid-1950s. However, the Biarritz's popularity declined afterward, but it soldiered on until 1991. That year, the Biarritz enjoyed its final soirée. Cadillac's Final Crème De La Crème Eldorado Bring A Trailer The Biarritz trim was offered for the final time alongside the Eldorado's 11th generation. The 11th-gen iteration of the storied Caddy model was much smaller than it had been in previous years, as General Motors had downsized its entire full-size lineup for a second time in 1985. The reason behind shrinking dimensions was a prediction that fuel prices would rise sharply throughout the end of the 1980s. This prediction proved incorrect, however.Regardless, General Motors had committed, and the 11th-gen Eldorado was launched with an overall length of just under 16 feet — 15.95 to be exact — which is shorter than a modern-day Dodge Charger.Biarritz-trimmed Eldorados produced during the model's 11th generation didn't add any length to the Eldo, per se, but it did add a huge amount of luxury to the personal luxury coupe. Reportedly, the package alone tacked an additional $3,180 to the '91 Eldorado's price. In today's money, that's roughly an extra $7,600. With that sort of price tag, the Biarritz trim needed to be good. What The Biarritz Offered Bring A TrailerYou couldn't get more luxurious than you could with the '91 Eldorado than you could with the Biarritz trim, plain and simple.Starting off with its exterior, Biarritz-spec Eldorados received some unique upgrades. For starters, buyers had a choice between a slick top or a Landau roof, the latter being a half-vinyl, half-metal configuration, with the vinyl top situated at the rear. A Biarritz badge adorned either side of the model's exterior C-Pillars written in a familiar, cursive font. A special set of alloy wheels was also included in the package, along with a few extra smatterings of chrome found on the front fascia.Bring A Trailer Inside, the Biarritz package became much more apparent. A 10-way powered driver's seat came standard, and all seats were upholstered with quilted leather with a litany of special colors on offer. Buyers could also choose to select contrasting carpet colors. For example, Biarritz buyers could spring for white leather seats and navy blue carpet. A pair of rear C-Pillar-mounted reading lights was also included, a feature normally reserved as an option on other Eldorado grades.Bring A Trailer A unique Delco-Bose sound system came standard with the Biarritz package, an option that normally cost upwards of $400 during the Eldorado's 11th generation. In addition, the package included some other Caddy standards, like a fully digital dashboard, automatic climate control, and GM's Twilight Sentinel, which allowed the Eldo's headlights to remain lit after the car was shut off, the timing of which could be adjusted. A theft-deterrent system also came standard, a piece of kit that normally cost about $480 on other, less-luxurious Eldorado grades.Bring A Trailer An even-rarer Biarritz package, coined the "Biarritz Gold Edition" was offered, too. Selecting the Gold Edition swapped out all silver badges and emblems for gold ones, and included a special set of wheels. All told, roughly 16,212 Cadillac Eldorados were sold during its 1991 model year, which happened to be the final year of the 11th generation. Sadly, no concrete evidence exists for just how many Biarritz-trimmed examples were produced that year. Under The Hood Bring A TrailerWhile the Biarritz grade touched virtually everything, it didn't work its magic on the Eldo's underpinnings. Regardless, things were still luxury oriented under the skin.Sitting atop the 11th-gen Eldorado's front-wheel-drive drivetrain was a Cadillac-bred 4.9-liter V8, which was introduced for the 1991 model year. The mill itself belonged to Cadillac's High Technology engine family, and boasted some space-age tech for its time. Features like port fuel injection and a "square" configuration, wherein both the engine's bore and stroke measured virtually the same. Many folks consider the 4.9-liter Cadillac V8 to be the last "old-school" engine built by the brand before the troubled Northstar V8 was introduced in 1993.Bring A Trailer Handling the 4.9-liter engine's power is a four-speed 4T60-E automatic transmission. Interestingly, Cadillac designed its own clutch, called the viscous coupler clutch by the brand, that smoothed out shifting when the car was exposed to hard driving. As for its suspension setup, the '91 Eldorado took advantage of a fully independent setup, consisting of something called the Computer Command Ride (CCR). The CCR tech allows for three separate suspension dampening settings, ranging from Comfort, to Normal, then Firm. The model's rear suspension boasts automatic pneumatic leveling.Bring A Trailer History Of The Biarritz And The End Of The Eldorado CadillacBeginning in 1956, Cadillac began offering the Biarritz trim package. Back then, it was relegated to the convertible version of the Eldorado, as the hardtop iteration was called the Eldorado Seville. Throughout the 1950s, the Biarritz remained as the Eldorado's convertible option. During the early 1960s, the Biarritz-grade Eldorado retained its convertible status, although the hard-topped Eldorado had dropped the Seville namesake. The Biarritz name would then receive the axe following the 1964 model year.Bring a Trailer However, Cadillac decided to resurrect the iconic namesake in 1976. This time, it wouldn't just be a convertible version of the Eldorado. Instead, the Biarritz namesake was attached to the model's highest-spec trim level.Offered with the package came unique upgrades like a padded Landau roof, opera windows – a staple in the late-1970s personal luxury coupe market – and a slew of digital options like a gauge cluster, climate control center, and driver information center, the latter of which displayed info like fuel economy and trip mileage.Once downsizing took effect for the first time following the 1978 model year, the Biarritz trim followed the Eldorado. New for the smaller '79 Eldo Biarritz was an all-new, smaller 5.7-liter V8, which also powered lower-sped Eldorados, as well. In addition, four-wheel disc brakes became standard, as well. Another new addition for the 1979 model year was a stainless steel roof panel for models that were not Landau-equipped.Bring A Trailer With the axing of the Biarritz trim level in 1991, the Cadillac Eldorado as a whole held on for a bit longer. The model's 12th, and final, generation was introduced for the 1992 model year. For the first time since the early 1970s, the Eldo ended up growing in size, as GM was beginning to leave behind some of its downsizing tendencies as engines became more efficient, as well as powerful.Sales continued until 2002, with the model suffering from a slow decline in interest as personal luxury coupes fell out of favor.