Carroll Shelby, who had won the 24 Hours of Le Mans in 1959, recognised that the open-cockpit Cobra was fundamentally limited on circuits with long high-speed straights. On the Mulsanne Straight at Le Mans the roadster was restricted to around 157 mph, nearly 30 mph slower than Ferrari's 250 GTO, a deficit that translated to more than ten seconds per lap and erased any advantage the Cobra held in slower sections. The solution required a fully enclosed aerodynamic body.
Shelby assigned Pete Brock to design the bodywork, drawing on German aerodynamic engineering designs from the late 1930s, copies of which were found in the Ford archive after being thought lost during World War II. Bob Negstad handled the chassis and suspension, work he also performed on the GT40 and the coil-spring Cobra. Brock built the prototype using scrap wood and gaffer tape to establish the windscreen geometry, then hand-formed aluminium panels around wooden formers over a chassis salvaged from the 1963 Le Mans race. An aerodynamics consultant from Convair, Ben Howard, argued that the tail needed extending by at least three feet, but Brock stood firm on his design.
The first car, chassis CSX2287, was completed at the Shelby American shop in Venice, California. Driver Ken Miles took it to Riverside Raceway for initial testing and recorded speeds over 190 mph on the main straight. The remaining five coupes were built at Carrozzeria Gransport in Modena, Italy.
The Shelby Daytona Coupes competed in GT Division III, covering engine displacements above 2000 cc, across a calendar of 500 km, 1000 km, 12-hour, and 24-hour races on the International Championship for GT Manufacturers series. Venues included Le Mans, Daytona, Sebring, Imola, Reims, Spa-Francorchamps, Goodwood, Oulton Park, the Nurburgring, and the Tour de France Automobile.
In 1964, the first full season of competition, the coupes finished second in the GT III class championship, six points behind Ferrari. Key results that year included a GT class win and fourth overall at the 12 Hours of Sebring for Dave MacDonald and Bob Holbert, a GT class win and fourth overall at the 24 Hours of Le Mans for Dan Gurney and Bob Bondurant, and a GT class win at the RAC Tourist Trophy. Chassis CSX2299, the first coupe completed at Carrozzeria Gransport, recorded GT class-winning lap records at Le Mans, Reims, and Rouen and the race-distance record at Le Mans and Goodwood.
In 1965 the coupes won the GT III class championship by 19 points, securing the title at Reims in July where Bob Bondurant and Jo Schlesser drove CSX2601 to a GT class victory. The 1965 season also produced GT class wins at Daytona, Sebring, Monza, the Nurburgring, and Enna-Pergusa, and chassis CSX2287 set 25 USAC and FIA land speed records at the Bonneville Salt Flats.
CSX2287, the prototype built in Venice, carried drivers including Dave MacDonald, Bob Holbert, Phil Hill, Chris Amon, Ken Miles, Innes Ireland, and Jo Schlesser. After its racing career ended at Bonneville it passed through the hands of slot-car magnate Jim Russell and music producer Phil Spector before disappearing in the mid-1970s. The car was rediscovered in 2001 in a California storage unit and, after a legal dispute over ownership, was acquired by Dr. Frederick A. Simeone. It is now part of the permanent collection of the Simeone Foundation Automotive Museum in Philadelphia. In January 2014 it became the first vehicle added to the Historic Vehicle Association's National Historic Vehicle Register and the first automobile documented under the United States Secretary of the Interior Standards for Heritage Documentation, held in the Library of Congress.
CSX2299, the second coupe, competed in nine FIA races between 1964 and 1965, winning four FIA events. It is currently owned by the Larry H. Miller Group and is displayed at the Shelby American Collection in Boulder, Colorado.
CSX2601, the fourth coupe, clinched the 1965 manufacturers' title at Reims and was later featured in the 1965 film Red Line 7000. It sold for $7.25 million in August 2009.
CSX2300 was temporarily raced by a French national team in the 1965 Nurburgring 1000 km before returning to Alan Mann Racing. Carroll Shelby himself owned the car before it sold at auction for $4.4 million in August 2000.
The Shelby Daytona program stands as one of the decisive episodes in the 1960s transatlantic battle between American and Italian motorsport ambition. Carroll Shelby set out to beat Enzo Ferrari on Ferrari's home ground using aerodynamic science, Ford horsepower, and a small team of California fabricators, and in 1965 he succeeded. The first American constructor's title in FIA World Championship history was the result. The surviving coupes remain among the most historically significant and valuable American racing cars ever built.