From the AP:
It was McDowell’s first victory in 358 Cup Series starts, a stunning upset in NASCAR’s signature event. McDowell lead just one lap — the only that mattered.
McDowell was running third when Keselowski got a huge run on Logano. Keselowski tried to pass Logano on the low side, but Logano tried to block him and ended up crashing both of them.
Hamlin was trying to become the first in NASCAR history to win three consecutive Daytona 500s.