The American classic muscle car era kicked off in the mid-1960s. While the exact origins of the muscle car as a whole are contested, most folks agree that the first definitive muscle car was the 1964 Pontiac GTO. It was the first purpose-built model to really nail down the recipe with a big V8 shoehorned into a light, mid-size car. Once the GTO hit the market, nearly every other automaker rushed to create their own high-performance mid-size car to compete with it, thus giving birth to the coveted classic muscle car era as we know it.Few folks remember that the second muscle car to come after the 1964 GTO was an Oldsmobile. It was called the Cutlass, or F-85, and followed the GTO's groundbreaking combination nearly to a T. However, just six years after that first Olds muscle car hit the streets, Oldsmobile came up with something a bit more highbrow. It was called the Cutlass SX, and on the outside, it was just a normal, luxury-oriented Cutlass Supreme. However, underneath the hood, you could have up to 365 horsepower, making it one of the most venerable factory-built sleepers of its time. High Class & Hot Camshafts Bring A Trailer Quick Facts About The Oldsmobile Cutlass SX Introduced in 1970 Offered two engine options, the latter of which produced 365 horsepower Came as both a coupe or convertible body style Technically considered a performance package for the Cutlass Supreme known as "Y79" Axed following the 1971 model year Roughly 10 years prior to the sleeper SX's introduction, the Cutlass model as a whole was launched. In the late 1950s, General Motors was beginning to read the writing on the proverbial walls. Many Americans were beginning to tire of the increasingly large coupes and sedans being pushed by the Detroit Big Three, and GM wanted to get ahead of the upcoming game. So, the GM Z Platform was introduced, which carried models like the Chevrolet Corvair.Bring A Trailer Oldsmobile was slated to join in on the new-found compact segment fun, but in a slightly different way. Because Olds was a bit more luxurious than Chevrolet or Pontiac, GM declared that Oldsmobile's compact car would be built on something called the Y Platform, also known as the "senior compact platform". The first model to take advantage of the Y Platform was the Cutlass, or F-85, introduced in 1961. A single engine, a 215 CID V8, was on offer. The first turbocharged production car ever, the Oldsmobile Jetfire, was based on the 1962 and 1963 Cutlass and took advantage of an all-aluminum version of the aforementioned 215 CID engine.Mecum Once the Cutlass entered its second generation in 1964, Oldsmobile decided to up the performance ante. The Cutlass began to offer a 330 CID option, beginning in 1964, which meant it could now compete with the hot Pontiac GTO. Olds introduced the 4-4-2 that same year, which was a high-performance version of the Cutlass and Oldsmobile's first purpose-built muscle car. Beginning in 1965, the 4-4-2 began to offer a larger, 400 CID V8 based on Oldsmobile's BO-9 Police Package. Enter The Sneaky SX 1970 oldsmobile cutlass sx full_frontalThe third-gen Cutlass debuted in 1968 with radical new, fastback styling. The 4-4-2 remained on Oldsmobile's model lineup as its king of performance. However, come 1970, Olds was keen to provide a huge chunk of power to a slightly different, more subtle buyer. That's where the Cutlass SX comes in, with all its opulence and high price tag. Oldsmobile knew that some older gentlemen were passing up the opportunity to own a 4-4-2 simply because it was seen as a little bit juvenile.Bring A Trailer So, instead of trying to revamp the 4-4-2 and, potentially, alienate the majority of buyers who were already interested in the hot model, Oldsmobile created a slightly different, high-performance model coined the Cutlass SX. In essence, the SX was simply a performance package offered on the top-spec Cutlass Supreme. You could have virtually the same big-block 455 CID V8 found in the 4-4-2, but without the optional spoiler or body decals and badges that said "4-4-2" on them. Because of this, only the most keen-eyed Oldsmobile fans would be able to spot a Cutlass SX in a crowd, making it the perfect sleeper car.Bring A Trailer However, the Cutlass SX wasn't a huge hit, especially considering it was only produced for a niche market. According to most sources, roughly 9,374 Cutlass SXs were produced, with the vast majority being 1970 model-years. For contrast, Olds managed to shift approximately just over 30,000 4-4-2 models during the 1970 and 1971 model years. So, with two-thirds less sales that slowed drastically, and a price tag similar to the 4-4-2 without some of the go-faster bits found in it, the Cutlass SX was canned from the lineup following the 1971 model year. Under Its Unassuming Skin Bring A TrailerIn total, three engine options were offered on the Cutlass SX, all of which consisted of Oldsmobile's big-block 455 CID V8. At base level sat the L33 engine, which managed to produce 320 SAE gross horsepower and 500 lb-ft of torque. The L33 sported a two-barrel carburetor. However, come mid-1970, the L33 was dropped in favor of the L31 455 CID V8, which added a four-barrel carburetor. This upped the power to 365 horsepower and 500 lb-ft of torque.Bring A Trailer The third option was the Oldsmobile W-32 performance option, which was the same motor offered in the automatic version of the Oldsmobile 4-4-2. In 1971, all Cutlass SX engines were dropped in favor of an Oldsmobile L32. It was still a 455 CID big-block, but it only produced 250 SAE net horsepower.Bring A Trailer As the Cutlass SX was supposed to be a luxury coupe of sorts, it only offered a Turbo-Hydramatic TH400 three-speed automatic transmission. As you could imagine, rear-wheel drive was the sole drivetrain option. At base level, the Cutlass SX offered the same suspension setup seen on the Cutlass Supreme. However, buyers could spring for the heavy-duty upgrade called the "Rallye Suspension" or "FE2" package. The option added things like stiffer springs and shocks, along with beefed-up control arms. An upgraded rear differential and aluminum axle carrier package coined "W-27" was offered, but it's reported than no Cutlass SXs or Supremes left the factory with this option.Bring A Trailer*Specs courtesy of Dezo's Garage & Oldsmobiles Forever The Cutlass SX: The High-Class 4-4-2 Bring A TrailerSome of you may be aware of current Oldsmobile 4-4-2 pricing, especially for 1970 and 1971 models. These days, 4-4-2s falling into those model years regularly fetch prices of around $41,900 when in excellent condition, according to Hagerty. However, Cutlass SXs go for a bit more. Again referencing Hagerty, the Cutlass SX usually lists for around $43,800 in excellent condition. A bit more expensive than the fully fledged 4-4-2 muscle car, it's much rarer, more luxurious, and guaranteed to raise a few more eyebrows. Not to mention, you could line one up next to an unsuspecting Chevelle or GTO and have a fighting chance.*Pricing courtesy of Hagerty