Gurney stayed with Shelby-American for their 1967 World Sportscar Championship campaign. Things were not going smoothly in development of Ford's next Prototype entry. After problems highlighted by the fatal accident of Ken Miles in testing the Mark III "J Car," another iteration was designed but it would not be built in time for the season opener at the 24 Hours of Daytona. After a dismal showing at Daytona with the Mk II, Shelby introduced the Mk IV at the 12 Hours of Sebring with a resounding win. After that demonstration the Mk IVs were held in preparation for Le Mans, with Ford's hopes for a repeat championship resting on the GT40s and GT40-derived Mirages campaigned by other teams in the intervening races. A controversial decision to withhold points from the Mirage win at the Spa 1000 km event from Ford's season credit virtually killed hopes for a repeat championship and gave Le Mans an all-or-nothing aspect for Ford. Four Mk IVs were entered, two with Shelby-American and two with Holman and Moody, Ford's unofficial NASCAR team.