CHARLOTTE, N.C. -- Jason Leffler would have had a better chance of surviving his fatal crash in a winged sprint car in New Jersey if he'd had a full containment headrest similar to what is used in NASCAR, multiple safety experts told ESPN.com.

Leffler, 37, was killed in the June 12 race at Bridgeport Speedway when his 410 sprint car suddenly veered into the wall and then rolled multiple times.

Racing safety pioneer Bill Simpson and Randy LaJoie, a two-time Nationwide Series champion who now designs and builds race car seats, have studied the wreck. They agree that a 180-degree surround headrest might have saved Leffler's life at the 0.625-mile dirt track.

Medical examiner Dr. Fredric Hellman, who performed the autopsy, said the death resulted from a blunt-force neck injury caused by a head-whip-type motion.

New Jersey State Police have not released results of their investigation, although Simpson and others who have looked into the wreck have been told by those at the track that a failed part on the front end likely caused the car to angle into the wall at a high speed.

LaJoie, who once served on the New Jersey safety board, has been in contact with investigators regarding the accident. Simpson has talked to mechanics and other eyewitnesses who were at the track.

Both were told that Leffler, who was wearing a head and neck restraint designed to protect on frontal impacts, did not have a headrest sufficient enough to keep his head in line with the rest of his body on a lateral impact.

"My findings showed everything with the head and neck restraint is fine when you have a forward impact as long as it doesn't go past 30 degrees, from one side to the other," Simpson said. "There is no lateral protection with the head and neck restraint. Nothing.

"Your head can flop from side to side. There is nothing to stop it from doing that. That car that Leffler was driving, it did not have a 180-degree head surround like a [Sprint] Cup car has. When he crashed and landed on his side and stopped, his head kept going."

LaJoie agreed. "He wasn't contained," he said. "That's why we haven't killed anyone in NASCAR, because we learned not to let the body and head move. Your head, chest and pelvis need to stay in line as close as possible."