It seems that several different automobiles were used as "Official Cars" at the events held at Sebring in 1967. Pictures taken at both the 4-Hour International Trans-American Championship Race for the Florida Governors Trophy which took place on Friday, March 31, 1967 and the 12 Hours of Endurance for the Alitalia Trophy run the next day on Saturday, April 1, 1967 demonstrate that a white 1967 Mustang, a silver 1967 Mustang 2+2, a white 1967 Mercedes-Benz 230 SL and a white 1967 Ford Fairlane GTA were all used in some official capacity. Neither the Trans Am race or the 12-Hour endurance race used a rolling start to begin the race, so none of these cars were used to actually "pace" the race.
These two photos of Ms. Sebring sitting on the white 1967 Mustang came from here:
https://sebringrace.com/