DARLINGTON, SC - SEPTEMBER 04: Dale Earnhardt Jr. (L) spaeks as Rick Hendrick, owner of Hendrick Motorsports, and Dr. Micky Collins of the University of Pittsburgh Medical Center Sports Medicine Concussion Program, listen during a press conference prior to the NASCAR Sprint Cup Series Bojangles' Southern 500 at Darlington Raceway on September 4, 2016 in Darlington, South Carolina. (Photo by Blaine Ohigashi/Getty Images)

DARLINGTON, SC - SEPTEMBER 04: Rick Hendrick, owner of Hendrick Motorsports speaks during a press conference with Dale Earnhardt Jr. prior to the NASCAR Sprint Cup Series Bojangles' Southern 500 at Darlington Raceway on September 4, 2016 in Darlington, South Carolina. (Photo by Blaine Ohigashi/Getty Images)

DARLINGTON, SC - SEPTEMBER 04: Dale Earnhardt Jr. speaks to the media during the NASCAR Sprint Cup Series Bojangles' Southern 500 at Darlington Raceway on September 4, 2016 in Darlington, South Carolina. (Photo by Blaine Ohigashi/Getty Images)

DARLINGTON, SC - SEPTEMBER 04: Dale Earnhardt Jr. speaks to the media during the NASCAR Sprint Cup Series Bojangles' Southern 500 at Darlington Raceway on September 4, 2016 in Darlington, South Carolina. (Photo by Blaine Ohigashi/Getty Images)

DARLINGTON, SC - SEPTEMBER 04: Dale Earnhardt Jr. speaks to the media during the NASCAR Sprint Cup Series Bojangles' Southern 500 at Darlington Raceway on September 4, 2016 in Darlington, South Carolina. (Photo by Blaine Ohigashi/Getty Images)

DARLINGTON, SC - SEPTEMBER 04: Dale Earnhardt Jr. speaks to the media during the NASCAR Sprint Cup Series Bojangles' Southern 500 at Darlington Raceway on September 4, 2016 in Darlington, South Carolina. (Photo by Blaine Ohigashi/Getty Images)

MONZA, ITALY - SEPTEMBER 04: Valtteri Bottas of Finland driving the (77) Williams Martini Racing Williams FW38 Mercedes PU106C Hybrid turbo leads Jenson Button of Great Britain driving the (22) McLaren Honda Formula 1 Team McLaren MP4-31 Honda RA616H Hybrid turbo on track during the Formula One Grand Prix of Italy at Autodromo di Monza on September 4, 2016 in Monza, Italy. (Photo by Mark Thompson/Getty Images)

MONZA, ITALY - SEPTEMBER 04: Jenson Button of Great Britain driving the (22) McLaren Honda Formula 1 Team McLaren MP4-31 Honda RA616H Hybrid turbo leads Marcus Ericsson of Sweden driving the (9) Sauber F1 Team Sauber C35 Ferrari 059/5 turbo and Esteban Gutierrez of Mexico driving the (21) Haas F1 Team Haas-Ferrari VF-16 Ferrari 059/5 turbo on track during the Formula One Grand Prix of Italy at Autodromo di Monza on September 4, 2016 in Monza, Italy. (Photo by Mark Thompson/Getty Images)