Brian Vickers 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., Thursday, May 22, 2014. (AP Photo/Mike McCarn)
Kevin Harvick talks to a crew member before practice for Sunday's NASCAR Sprint Cup series Coca-Cola 600 auto race at Charlotte Motor Speedway in Concord, N.C., Thursday, May 22, 2014. (AP Photo/Terry Renna)
Matt Kenseth waits in his car before practice for Sunday's NASCAR Sprint Cup series Coca-Cola 600 auto race at Charlotte Motor Speedway in Concord, N.C., Thursday, May 22, 2014. (AP Photo/Terry Renna)
Brad Keselowski, center, signs autographs before practice for Sunday's NASCAR Sprint Cup series Coca-Cola 600 auto race at Charlotte Motor Speedway in Concord, N.C., Thursday, May 22, 2014. (AP Photo/Mike McCarn)
Jeff Gordon talks to crew members before practice for Sunday's NASCAR Sprint Cup series Coca-Cola 600 auto race at Charlotte Motor Speedway in Concord, N.C., Thursday, May 22, 2014. (AP Photo/Terry Renna)
Danica Patrick prepares before practice for Sunday's NASCAR Sprint Cup series auto race at Charlotte Motor Speedway in Concord, N.C., Thursday, May 22, 2014. (AP Photo/Mike McCarn)
Kyle Bushc, left, talks with Dale Earnhardt Jr, right, before practice for Sunday's NASCAR Sprint Cup series Coca-Cola 600 auto race at Charlotte Motor Speedway in Concord, N.C., Thursday, May 22, 2014. (AP Photo/Mike McCarn)
Jamie McMurray walks through the garage during practice for Sunday's NASCAR Sprint Cup series auto race at Charlotte Motor Speedway in Concord, N.C., Thursday, May 22, 2014. (AP Photo/Mike McCarn)
Jimmie Johnson prepares before practice for Sunday's NASCAR Sprint Cup series Coca-Cola 600 auto race at Charlotte Motor Speedway in Concord, N.C., Thursday, May 22, 2014. (AP Photo/Mike McCarn)