Hertz and Shelby are working together again. To celebrate a partnership spanning over half a century, the two companies have teamed up on some all-new Shelby GT-H rental Mustangs. One of them has 900 horsepower. This might not be a good idea.

Hertz and Shelby started working together back in 1966 when 1,000 Mustang GT350s were sent to the rental company’s fleet. Finished in black with gold stripes, the cars were later sold to the public as Shelby GT-H models. The returned with the. Just 500 coupes and 500 convertibles were made between 2006 and . All had the 319-horsepower 4.6-liter V8.

Now, Hertz renters will get to choose between two flavors of Shelby Mustang. The “basic” version will be the GT-H, shown above, which has special paint and wheels but is otherwise no different from a run-of-the-mill Fun Collection Mustang—pretty much a stock GT with a performance exhaust system.

You don’t want that one, though. The one you want is the bonkers GT500-H. Hertz started with the 760-hp Shelby GT500 and replaced the factory Roots-type supercharger with a 3.8-liter Whipple unit. A bigger throttle body, cold-air intake, and dual-pass intercoolers bring power output to 900 hp, a 140-hp increase over a standard GT500. Aluminum wheels with performance tires, tinted windows, special badging, and a carbon fiber hood make up the exterior changes. Nineteen of the GT500-Hs will have shadow black paint and six will be painted white. Hertz CEO Stephen Scherr says that “Hertz and Shelby American have created driving magic again.”

Except that magic might be tainted. Putting a 900-horsepower special edition muscle car in the hands of renters doesn’t seem like the soundest idea. At a time when Hertz is under for allegedly , adding a high-power, extremely limited-edition muscle car to the mix is certainly an odd choice. The Shelby/Hertz partnership is expected to last three years, and the GT500-H will only be available at select airport locations.

Update: Hertz got back to me with more details on the Mustangs.

Both models will be available starting this summerThe average daily rate for the GT-H coupe and convertibles will be $99/day; GT500-H average daily rate will be $399/day.There will only be 25 GT500-H and 400 GT-Hs

GT-H will be available in Atlanta, Dallas, Fort Lauderdale, Fort Myers, Las Vegas, Los Angeles Miami, Orlando, Phoenix, San Diego, San Francisco, and Tampa.GT500-H will be available in Fort Myers, Las Vegas, Miami, Orlando, Phoenix, and Tampa.