Kurt Busch climbs into his car before practice for Sunday's NASCAR Sprint Cup series Coca-Cola 600 auto race at Charlotte Motor Speedway in Concord, N.C., Saturday, May 24, 2014. (AP Photo/Chris Keane)
Kurt Busch drives his car from the garage during practice for Sunday's NASCAR Sprint Cup series Coca-Cola 600 auto race at Charlotte Motor Speedway in Concord, N.C., Saturday, May 24, 2014. (AP Photo/Terry Renna)
Dale Earnhardt Jr. looks over his car during practice for Sunday's NASCAR Sprint Cup series Coca-Cola 600 auto race at Charlotte Motor Speedway in Concord, N.C., Saturday, May 24, 2014. (AP Photo/Chris Keane)