Shelby builds 600-hp GT-S for Sixt fleet

20 cars will trickle into select Sixt locations this summer.

Horsepower aficionados might luck out the next time they play rental car roulette. Well-known tuner Shelby American has teamed up with Sixt to add at least 20 high-performance Ford Mustang fastbacks to the renter's fleet in select American states.

The Sixt-specific Mustang is called Shelby GT-S. Visually, it's recognizable thanks to an orange and black two-tone paint job inspired by the German car renter's logo. Some cars are finished in orange with black racing stripes; others will wear the opposite combination. Regardless of color, the GT-S gains a full body kit that includes a Shelby-specific front bumper and a rear wing, a redesigned grille that looks almost Ram-like to us, 20-inch alloy wheels, an array of emblems, and a redesigned interior with leather upholstery.

Power comes from a supercharged, 5.0-liter V8 engine tuned to make over 600 horsepower; Shelby hasn't revealed more specific technical details. We know the eight-cylinder spins the rear wheels through a 10-speed automatic transmission. Suspension components sourced from Ford Performance and Brembo front brakes keep the cavalry in check.

According to Sixt, the first batch of 20 cars will be available at select locations in southern California, southern Florida, and Las Vegas. Shelby hasn't announced plans to build more cars yet, but the announcement's wording suggests the first batch won't be the last, so enthusiasts in other states might have the opportunity to slip behind the wheel of the GT-S sooner or later.

Every Shelby GT-S will join the company's registry. When their time in the Sixt fleet is up, they will return to the tuner's headquarters in Las Vegas and they will be sold to collectors. Previous limited-edition variants of the Mustang developed for rental car companies (Hertz, notably) have gained a tremendous amount of value as they aged, and the GT-S will likely be no exception. In other words: keep your eye on the local classifieds if you're looking for a future classic.