EXP, in the case of the 1968 Ford Mustang you see above, stands for Experimental. You see, this is one of the cars used by the Shelby American team in the development of a long list of classic ...

According to Shelby Prototype Coupes, Ford handed the Lime Gold prototype over to Shelby Automotive in 1968, where the prototype picked up the EXP-500 moniker.

Two cars stand out in his classic car collection. A one-off 1967 Ford Shelby GT500 EXP prototype, aka 'Little Red,' and a 1968 Shelby Mustang EXP-500 Prototype, aka 'Green Hornet.' ...

A 1968 Ford Mustang from Carroll Shelby's personal collection is up for grabs. Nicknamed Black Hornet, it's scheduled to be auctioned off by Barrett-Jackson at the company's Scottsdale, Arizona ...

You've heard of some of the other "EXP" cars: Super Snake, Green Hornet, Little Red, and the '08 twin-turbo Code Red. Shelby American's been building Shelby GT500 EXPs since 1967. See All 4 Photos ...

The Shelby GT-500 isn't the only high-performance Mustang. Saleen, a global supercar maker and tuner, builds complete Mustangs for each generation. Like Porsche's Gemballa, RUF, or TechArt, Saleen ...

According to its lengthy listing in the Registry, the Lime Gold GT 500 was released to Shelby American's engineering department on February 3, 1967, for use as a factory test car.