Muscle cars were not designed to be rare. During the '60s, dealerships were selling these V8-powered two-door models as fast as they could build them, and almost every carmaker in America was rushing to bring ever-more powerful models to the market. But for all the commotion over the latest mass-produced muscle, there were a few that remained as rare as hen's teeth. These could be obscure trim levels, or specials designed for drag racing, but these days they all carry a hefty price tag – if you can get hold of one, of course.The models on this list have been extensively researched with all information verified to the best of our ability. Models are ranked from the lowest estimated value to the highest estimated value. HotCars used experts Hagerty.com and Classic.com for prices, as well as looking at recent sales. The models in this list were built in Detroit or the Detroit area. 1970 Ford Mustang Twister Special Estimated Value: $150,000 MecumThe 1970 Ford Mustang Twister Special is a rare car that happened almost by accident. At the start of the '70s, a racing organization put in a special order for 96 Grabber Orange Mustangs to be used as pace cars and limited editions. Just as the order was being completed, the organization went out of business, meaning the cars were sitting around gathering dust. The Unwanted Mustangs Were Turned Into Sought-After Classics Mecum As a stroke of marketing genius, it was decided that the cars would be rebranded as Twister Specials and sold in dealerships in Kansas, Northwest Arkansas, and Western Missouri, which were all areas connected to Tornado Alley. The Twister Special was equipped with either a 300-horsepower 351-inch Cleveland or a 428-inch V8 engine, and both of those options were split with either an auto or a four-speed manual transmission, meaning there are 24 of each configuration. There are no specific average prices for the 1970 Twister, but expect to pay around $150,000 based on recent sales. 1970 Ford Mustang Twister Special In Detail 1969 Plymouth Hemi Road Runner Coupe Estimated Value: $214,500 MecumThe mighty 425-horsepower 426 Hemi engine is an intimidating powerplant, with rumors suggesting that dealerships would only sell one to the more insistent of customers. But to get a gauge on how scary the Hemi was, just look at the number of 1969 Plymouth Hemi Road Runner Coupes sold with that engine. The Hemi Was A Rare Option In The Road Runner Mecum The Road Runner, with its iconic "Beep Beep" horn, was a desirable car at the end of the 60s, but most people went for the 383 up front, while fewer still opted for the 440 6-BBL models. According to Mecum, the 4-speed Hemi option was ticked by just 194 buyers for that year, making it incredibly rare. When one of these cars was sold in 2023, it went for $214,500. The rarest of all seems to be the convertible Hemi Road Runner, with just 12 being built. These are so rare we couldn't find a picture to include. 1969 Plymouth Hemi Road Runner Coupe In Detail 1969 Plymouth Hemi GTX Convertible Estimated Value: $230,000 MecumThe Plymouth Hemi GTX was a luxury version of the Road Runner with a large range of optional equipment. The 425-horsepower 426 Hemi V8 engine was offered for the car, but it remained a rarity, with hardly any customers ticking the box. Less Than A Dozen People Bought A Hemi GTX Convertible Mecum Just 11 Hemi GTX convertibles were produced in 1969, says Mecum, with just six produced with an automatic transmission. These cars could be optioned with a power top, factory electric windows, front bucket seats, a performance indicator vacuum gauge, variable speed wipers, and even a 150 mph speedometer. When one of the 11 rag-tops went up for sale in 2020, the price reached $230,000, but it failed to sell. 1969 Plymouth Hemi GTX Convertible In Detail 1970 Dodge Coronet R/T Hemi Estimated Value: $247,500 MecumThe Hemi engine may be legendary, but in 1970, it wasn't exactly popular. Dodge and Plymouth were building muscle cars by the tens of thousands at the beginning of the decade, but, according to Mecum Auctions, only around 1,500 of these came with the Elephant Engine. This is down to the 425-ci Hemi being a pricey option for the time, and with the Golden Era of muscle cars fading, buyers seemed content with lesser V8s. The Hemi And The Coronet Were A Rare Pairing Mecum But of those 1,500 Hemis, almost none found their way to the Dodge Coronet. Dodge only built 13 Coronet Hemi R/Ts in 1970 (Mecum), making this one of the rarest muscle cars of all time. If you want to get even rarer, just four Coronet R/T hardtops were specced with a Hemi engine and 4-speed manual gearbox, and there is thought to be just one R/T Hemi drop-top. These cars have 425 horsepower and 490 lb-ft of torque. A manual version sold via Mecum Auctions in 2023 for $247,500. 1970 Dodge Coronet R/T Hemi In Detail 1964 Ford Fairlane Thunderbolt Estimated Value: $253,000 Mecum AuctionsThe Ford Fairlane Thunderbolt arrived for 1964 with a 427-ci FE V8 with two 4-barrel carburetors and a ton of power. Officially, the peak power of this rare car was 425 horsepower, and the torque was 480 lb-ft, but it was thought that the real hp figure was likely closer to 500 or even 600 hp. The Fairlane Went On A Diet To Become A Thunderbolt Mecum AuctionsThe Fairlane Thunderbolt came about because the Ford drag racer of choice in the early 60s was the Galaxie, and it was just too heavy against the Super Duty Catalinas and Max Wedge Mopars. The smaller Fairlane 500 stepped in, with cars leaving the production line without niceties such as heaters, sound-deadening material, and radios, before Dearborn Steel Tubing would rework the engine bay to fit the huge 427 from Galaxies. The finished Thunderbolts weighed around 3200 pounds – the NHRA minimum to compete in the Super Stock class –, and in the end, a total of 100 Thunderbolts were produced (Classic.com), with 51 automatic versions, and 49 manual examples. Classic.com puts the average price of 1964 Fairlane Thunderbolts at $253,000. 1964 Ford Fairlane Thunderbolt In Detail 1963 Chevrolet Impala Z11 Estimated Value: $296,000 MecumThe year 1963 was a pretty wild time for drag racing. This is a time when “Swiss Cheese” Catalinas were tearing up the asphalt, cars where it was hard to tell if there were more holes than metal, and the year of the Impala Z11. The Chevrolet RPO code Z11 gave access to a very special W-engine, which started off as a 409, but had displacement bumped up to 427 thanks to a crankshaft with a 3.65-inch stroke pushing pistons in the 409’s standard 4.3125-inch bore. The Impala Z11 Had An Output To Match Some Modern Supercars Mecum The Z11's output was rated at 430 horsepower, but as was typical of the time, this was likely higher, possibly in the range of 500 horsepower or more. The mill was connected to a Borg-Warner T-10 four-speed gearbox, and for added stopping power, the Impala was fitted with the brakes from a Corvette Z06. Hagerty says 57 Impala Z11s were produced, but just 25 were made for 1963, and each is now worth about $296,000 in good condition. 1963 Chevrolet Impala Z11 In Detail 1967 Ford Shelby GT500 Super Snake Estimated Value: $2,200,000 MecumCarroll Shelby stuck a modified Police Interceptor 428-ci V8 into the Ford Mustang in 1967 to create the first GT500, a 355-horsepower monster that took the Blue Oval pony car to a whole new level. The GT500 sold well, with Ford shifting 2,048 units, according to Mecum Auctions. But there was a fiercer version of the GT500 that was a lot rarer – in fact, just one was built. The Super Snake Was Built For A Publicity Stunt Mecum Auctions Designed for a Goodyear tire promo event, the GT500 Super Snake was custom-built by Shelby to run for 500 miles at an average speed of 142 mph, proving the durability of the new Thunderbolt tire. The Super Snake used a purpose-built GT40 Mk II 427 engine with an output of 600 horsepower, along with a raft of upgrades throughout. When this one-off Super Snake went up for auction in 2019, it fetched $2.2 million, making it the most expensive Mustang ever sold at the time. 1967 Ford Shelby GT500 Super Snake In Detail 1971 Plymouth Hemi 'Cuda Convertible Estimated Value: $3,500,000+ MecumThe Plymouth Barracuda had only been launched in 1964, but by 1971, it felt like the end. The muscle car segment was dwindling, with an oil crisis and emissions regulations on the horizon. The Barracuda was updated with a new front end, but sales still dropped from 55,499 to 18,690 (Hagerty), and certain trims and engine configurations were destined to become unexpected unicorns in the world of muscle cars. The Hemi Cuda Convertible Is One Of The Most Valuable Muscle Cars Of All Time Mecum One of these was the 1971 Hemi Cuda convertible from the final year that buyers could order the 426 for the car. It turned out that just 12 Cuda convertibles were fitted with this mill, with just seven destined to stay in the USA, and the other five exported. Only three of the 12 were fitted with a four-speed manual transmission, according to Hagerty. These 425-horsepower drop-top muscle cars are worth big money these days, one selling for $3,500,000 in 2015, and another (pictured) reaching $4,800,000 in 2021, but didn't sell. 1971 Plymouth Hemi 'Cuda Convertible In Detail Sources: Mecum.com; Hagerty.com; Hemmings.com