Graham Rahal won the first of two Detroit Grand Prix races, easily holding off Scott Dixon on Saturday.
Rahal won the pole earlier in the day and became the seventh IndyCar driver to win the first seven races of the year. He raced to his fifth career victory and fourth in two-plus years for Rahal Letterman Lanigan Racing.
Rahal made a last-lap pass of James Hinchcliffe for his previous win last year, when he beat Hinchcliffe by eight-thousandths of a second in the closest finish for an IndyCar race at Texas.
His victory in Detroit was less dramatic, finishing six-plus seconds ahead of Dixon. Hinchcliffe was third.
Indianapolis 500 winner Takuma Sato finished eighth.