Only 3,354 Buyers Chose the 1965 Riviera’s Hidden Muscle Package – And Bill Burr Still Can’t Get Over It

Buick built the 1965 Riviera as a luxury coupe, then quietly optioned in a 360-horsepower 425 V8 for buyers who wanted it both ways. Fewer than 3,500 people checked that box, making the Gran Sport one of the rarest true muscle cars of the era. Decades later, Bill Burr got behind the wheel with Jay Leno – and left convinced it might be the meanest car he’s ever driven.

Buick spent the first half of the 1960s building the ultimate business-executive coupe, and then, almost as an afterthought, decided to make it fast. In 1965, for a modest option price, Riviera buyers could check a box marked “Gran Sport” and drive away with a 425-cubic-inch V8 breathing through two four-barrel carburetors — 360 horsepower and 465 lb-ft of torque wrapped inside a car that looked ready for a boardroom, not a burnout. Almost nobody checked that box. Of the roughly 34,586 Rivieras Buick built that year, fewer than 3,500 left the factory as true Gran Sports, which is why most muscle car fans have never actually stood next to one. Decades later, comedian Bill Burr climbed into a restored example alongside Jay Leno and came away calling it one of the meanest cars he had ever driven — high praise for a machine still wearing a necktie. This is the story of the 1965 Buick Riviera Gran Sport, the personal-luxury coupe that quietly out-muscled half of Detroit.

The clearest modern introduction to the car comes from a segment of Jay Leno’s Garage, where Leno — a longtime Riviera admirer — hands the keys to comedian and car enthusiast Bill Burr for a sunlit California drive. The two spend the outing doing what the show does best: half technical walk-around, half stand-up bit, with Burr needling Leno about the car’s excess and Leno needling right back. Viewers in the comments have zeroed in on the chemistry as much as the car itself, quoting lines back and forth about the Riviera’s over-the-top comfort and Burr’s deadpan reactions to just how smooth 465 lb-ft of torque can feel.

What the segment gets right is tone. The Riviera GS was never marketed as a drag-strip weapon the way a GTO or a 442 was — it was Buick’s answer to a very specific question: what if the fastest car in the showroom also had the nicest interior? Burr’s read on it, delivered somewhere between admiration and disbelief, is that the car manages to feel like a genuine performance machine and something your grandfather would have been proud to park in the driveway, at the same time. That contradiction is the entire point of the Gran Sport package, and it is why the segment resonates with viewers who show up expecting a straightforward review and leave with an appreciation for a very odd, very good car.

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By the mid-1960s, Buick had already established the Riviera as its answer to a very specific brief: build a personal luxury coupe sharp enough to compete with the Ford Thunderbird, engineered on its own dedicated platform rather than shared corporate bones. The car, styled under GM design chief Bill Mitchell with Ned Nickles doing much of the hands-on clay work, had been an instant hit since its 1963 debut. For 1965, Buick finally solved a styling problem that had dogged the car from the start — concealed headlights had been part of the original design concept but were dropped at the last minute for cost reasons in 1963. By 1965 the mechanism was sorted, and stacked quad headlights disappeared behind small grilles for the first time, giving the final year of the first-generation Riviera its cleanest face yet.

The Nailhead Engine Buick Almost Didn’t Build for a Personal Luxury Car

The heart of the Gran Sport package was Buick’s 425-cubic-inch “nailhead” V8, nicknamed for the unusually small, vertically mounted valves that resembled nail heads sticking out of the cylinder head. In Super Wildcat trim — the dual four-barrel setup that came standard on every Gran Sport — the engine was factory-rated at 360 horsepower and a genuinely substantial 465 lb-ft of torque, backed by a stronger camshaft, tighter piston rings, and reinforced internals to handle the extra airflow. Buick paired it with a 3.42:1 Positraction rear axle and a reduced-backpressure dual exhaust system, numbers that translated to a factory-tested 0-to-60 run of around 8 seconds and a top speed of roughly 127 mph — quick enough in 1965 to embarrass plenty of cars that looked far more aggressive doing it.

Why So Few Buyers Ever Checked the Box

Buick built an estimated 34,586 Rivieras for the 1965 model year, and by most tallies, fewer than 3,500 of them left the factory equipped with the Gran Sport package — a rarity rate under 10 percent. Part of that came down to price, and part came down to positioning: the Riviera itself was already a premium, image-conscious purchase, and the GS option leaned even further into an audience that wanted power without giving up the personal-luxury pretense the car was built around. The result is a machine that, unlike a Pontiac GTO or a Plymouth Road Runner, was never trying to advertise its performance to the world. It is a genuine sleeper, which is exactly why it tends to surprise people who encounter one for the first time — including, apparently, Bill Burr.

A Design That Still Reads as Restrained Muscle

Where a lot of mid-’60s muscle cars leaned on scoops, stripes, and badges to sell the performance story, the Riviera Gran Sport sold it through proportion. Bill Mitchell’s original Riviera shape — long hood, fastback-adjacent roofline, and for 1965, those newly concealed headlights — was already one of GM’s cleanest designs of the era, and the GS package changed almost nothing about it. A GS badge on the trunk, a firmer suspension tune, and a deeper exhaust note were often the only outward clues. That restraint is a big part of why the car still photographs and drives like something newer than its year, and why collectors who care about design as much as horsepower have kept pushing GS values upward for decades.

That collector interest shows up in the numbers. A rough driver-quality Gran Sport can still be found in roughly the same range as a common Chevelle, but well-documented, numbers-matching dual-quad cars have climbed steadily at auction as buyers realize how few survive unmolested. For anyone shopping one today, the checklist is straightforward: confirm the 425 Super Wildcat engine and its dual-carb setup against the trim tag, verify the Positraction rear end, and budget for the fact that nailhead-specific parts are harder to source than small-block Chevy pieces. It is a car that rewards patience, both in the search and behind the wheel.

Watch the full video above and let us know your thoughts in the comments.