Ladies and gentlemen, let me introduce you the rarest and the most expensive Mustang ever sold – the one-off 1967 Shelby GT500 Super Snake.

So what makes the 1967 Shelby GT500 Super Snake so valuable? As we mentioned before, it’s the only one in the world, but it’s more than just that. It’s also the most powerful and fastest Mustang produced by Shelby in the 1960s, packing a 427 cubic inch V8 from a Ford GT40 race car under the hood.

The SuperSnake was an engineering study that was the result of a suggestion by Carroll Shelby to Shelby America’s Chief Engineer, Fred Goodell. Shelby asked Goodell to put together a 1967 GT500 powered by a super high performance 427 engine which could be used a test vehicle by Goodyear. The car Goodell chose was a white fastback (serial # 67402F4A00544). It was given a lightweight 427 medium-rise GT40 MK II engine fitted with aluminum heads, aluminum water pump, mechanical lifters, a single 780CM Holley 4V carburetor and a unique “bundle of snakes” GT40-style exhaust header system. It also had a large oil cooler and remote filter, a 4-speed transmission and a 4.11 rear end with a Detroit Locker “No-Spin” center section. The car was topped off with special Guardsman Blue stripes running up and over the top in a narrow-wide-narrow row pattern.

As soon as it was completed it was shipped to Goodyear’s test track in San Angelo, Texas to tire testing. Goodyear invited a number of journalists for the occasion, including representatives from Time and Life magazines. Shelby drove around the track at speeds in excess of 150MPH. At one point he was clocked at a top speed of 170MPH. Then he handed it over to Goodell to do the actual testing because he had to be in Washington, D.C.. Goodell eventually established a record, averaging 142MPH for 500 miles.

The car was returned to Shelby American, in Los Angeles, and Goodell started looking for a buyer. He turned to Don McCain, a former Shelby American Field Sales Representative (who had also been responsible for the GT350 drag program). By 1967, McCain had left Shelby American to become the High Performance Sales Manager for Mel Burns Ford, a Shelby dealer in Long Beach, California with a reputation for performance car involvement.

McCain envisioned having Shelby American build 50 Super Snakes which would be sold exclusively through his dealership as a Shelby alternative to the 427-powered Camaros and Chevelles and 426 MoPars which were in a league above the standard Shelbys. However, when he tallied up the cost of everything – even using a slightly detuned and therefore less expensive 427 engine – the bottom line was a cool $7500.

That sticker price was just too high. There was no question that the Super Snake was a real stormer but when prospective buyers realized it was about the same price as a 427 Cobra, they usually bought the Cobra. The Super Snake was eventually bought by a pair of airline pilots who drag raced it on weekends.

The initial test car remains the only built, making it the most desirable Shelby Mustang in existence. When it sold for $1.3 million at Mecum’s Indianapolis auction in May of 2013, it also became the most expensive Mustang ever sold.