After disappointing race results, the engineering team was moved in 1964 to Dearborn, Michigan, USA, to design and build cars by its advanced developer, Kar Kraft.

[8] The "GT" in the car's name stands for grand touring, and the "40" its height in inches (1.02 m) measured at the top of the windscreen, the minimum allowed.

Enzo cut the deal off out of spite and Henry Ford II, enraged, directed his racing division to find a company that could build a Ferrari-beater on the world endurance-racing circuit.

[12] The first chassis built by Abbey Panels of Coventry was delivered on 16 March 1964, with fibreglass mouldings produced by Fibre Glass Engineering Ltd of Farnham.

This meant that the McLaren/Amon vehicle, which had started perhaps 60 feet (18 m) behind the Hulme-Miles car, would have covered slightly more ground over the 24 hours and would, in the event of a tie for first place, be the winner.

Secondly, Ford officials admitted later, the company's contentious relationship with Miles, its top contract driver, placed executives in a difficult position.

The J-car was a GT40 prototype that included several unique features, most notably an aluminium-honeycomb chassis-construction and a "bread-van" body-design that experimented with "Kammback" aerodynamic theories.

Miles' fatal accident was attributed at least partly to the unproven aerodynamics of the J-car design, and to the experimental chassis' strength that had no roll cage yet.

The high speeds achieved in that race caused a rule change, which already came into effect in 1968: the prototypes were limited to the capacity of 3.0 litres, the same as in Formula One since 1966.

The result was a resounding success for the Mk I at the 24 Hours of Le Mans, with Pedro Rodríguez and Lucien Bianchi having a clear lead over the Porsches driving the 'almighty' #9 car with the 'Gulf Oil' colors.

Later victories included the Grand Prix de Spa, 21st Annual Watkins Glen Sports Car Road Race and the 1000 km di Monza.

The X-1 was a roadster built to contest the Fall 1965 North American Pro Series, a forerunner of Can-Am, entered by the Bruce McLaren team and driven by Chris Amon.

In 1966, the three teams racing the Mk II (Chris Amon and Bruce McLaren, Denny Hulme and Ken Miles, and Dick Hutcherson and Ronnie Bucknum) dominated Le Mans,[25] taking European audiences by surprise and beating Ferrari to finish 1-2-3 in the standings.

For 1967, the Mk IIs were upgraded to "B" spec, with re-designed bodywork and twin Holley carburettors (giving an additional 11 kilowatts (15 hp; 15 PS)).

A batch of improperly heat-treated input shafts in the transaxles side-lined virtually every Ford in the race at the 24 Hours of Daytona, however, and Ferrari won 1–2–3.

A total of seven were built,[1] four with right-hand drive, with four headlamps (raised to meet US lighting standards), an expanded rear (for luggage room), softer shock absorbers, a center-mounted shift lever, and an ashtray.

[29] In order to bring the car into alignment with Ford's "in house" ideology at the time,[clarify] more restrictive partnerships were implemented with English firms.

The nickname "J-car" came from its construction to meet the new Appendix J regulations[30] introduced by the FIA in 1966;[31] the redesign resulted in the abandonment of the original Mk I/Mk II chassis.

During a test session at Riverside International Raceway in August 1966 with Ken Miles driving, the car suddenly went out of control at the end of its high-speed, one-mile-long (1.6 km) back straight.

The Mk IV had a long, streamlined shape, which gave it exceptional top speed, crucial to do well at Le Mans (a circuit made up predominantly of straight roads connecting tight corners)—the race it was ultimately built for.

[citation needed] Thanks to its streamlined aerodynamics, the car proved to be fastest in the field at Le Mans in 1967, achieving 213 mph on the 3.6-mile Mulsanne Straight.

Gurney also complained about the weight of the Mk IV, which was 600 pounds (270 kg) more than the Ferrari 330 P4, and, combined with its higher speed, put more stress on its brakes.

Foyt who had just won the 1967 Indianapolis 500) of backing completely off the throttle several hundred yards before the approach to the Mulsanne hairpin and virtually coasting into the braking area.

[29] The installation of the roll cage was ultimately credited by many with saving the life of Andretti, who crashed violently at the Esses during the 1967 Le Mans yet escaped with minor injuries.

Thus, Le Mans 1967 still remains both the only all-American victory in Le Mans history — American drivers (Dan Gurney and A. J. Foyt), team (Shelby-American Inc.), chassis constructor (Ford), engine manufacturer (Ford), and tyres (Goodyear) — as well as the only victory of a car designed and built entirely (both chassis and engine) in the United States.

Maintaining the vehicle's Mark nomenclature, the new cars would be referred to as GT40 Mk Vs. JW Engineering wished to complete the existing GT40 chassis numbers GT40P-1087, 1088 and 1089 prior to the beginning of Safir production; this, however, was very much delayed.

was hired to inspect the proposed build and engineer any changes to minimize known problems with the car, and upgrade safety to modern standards he thought prudent.

Metal fabricator Tennant Panels supplied the roof structure, and the balance of the chassis was completed by Safir with parts from Adams McCall Engineering.

A British company, Safir Engineering, which continued to produce a limited number of GT40s (the Mk V) in the 1980s under an agreement with Walter Hayes of Ford and John Wilmont of J.W.

The British television series The Avengers of the 1960s featured a Mk.1 painted silver in the 1965 episode From Venus With Love, used by the villains as a mobile, high-powered laser platform.