The actual level of driving ability possessed by the movie's actors varied wildly. Bedford couldn't drive at all and was only ever in the car for close-up type shots, with the production's driving instructor calling the actor's situation "hopeless". Montand and Sabàto faced significant challenges, both of them struggling with even basic skills. Garner, on the other hand, proved competent enough that he trained exclusively with iconic Shelby Cobra driver Bob Bondurant, with the actor's interest in cars growing greatly as a direct result of his involvement in the film. Garner's talents on the road became strong enough that some of the professional drivers, including Bondurant, remarked that the actor could have been a successful Grand Prix driver if he had not gone into making films; director Frankenheimer himself agreed. Garner's devotion to the part caused him to do his own stunt in the scene in which a fuel leak in his vehicle sets it on fire. Garner's car was fitted with a higher rollbar and had no seat, since he was too tall to fit in a contemporary F1 car.