The state police released some findings Friday from its not-yet-complete report on the June 12 crash at Bridgeport Speedway in Logan Township.
The report finds that Leffler was not able to turn as he came out of the fourth turn and spun out, slamming into the concrete wall along the side of the track.
The report does not say how fast Leffler was going, but says cars in the race were averaging 135 mph and hitting 150 mph on straightaways.
Blunt-force neck injuries are cited as his cause of death.
The 37-year-old Leffler was a two-time winner on the NASCAR Nationwide Series.