A competitive Mustang-based racer would have required $250,000 or more in customizations for each vehicle.

Ford seriously considered entering the Mustang in the 24 Hours of Le Mans endurance race before deciding to build a new GT.

Codenamed Project Silver, the Mustang was dismissed after engineers found that $250,000 or more in modifications would be required to make a competitive endurance racer, Ford CTO Raj Nair said at a recent event attended by Automotive News. The company also decided Le Mans was ill-suited to the Mustang brand.

"To be candid, I still wanted to do it," Nair said. "I was actually a little bit mad ... in fact, I was really mad."

Committed to properly celebrating the 50th anniversary of Henry Ford and Carol Shelby's win over Ferrari, Nair claims to have gathered a dozen workers to work on the modern GT in secret. CEO Mark Fields and other executives were not initially privy to 'Project Phoenix.'

"This was going to be a test bed for our technologies for engine development that had to push the boundaries of material usage such as the lightweight carbon fiber that eventually ended up in the car, and had to stretch our understanding of what was possible with aerodynamics," Nair added.

Once the project gained traction, Nair claims to have invited individual executives down to the secret room in the company's Dearborn development center to receive a product pitch. The strategy appears to have been well played, as the GT was approved for production and finished first at Le Mans.