The 31-year-old Canadian, who started 11th in the field of 22, won his sixth career IndyCar race and first since last year at Long Beach by taking the 432-kilometre, 300-lap oval event for the second time at Newton, Iowa.
“This is such a good feeling after what happened in May,” Hinchcliffe said, noting his Indy 500 flop. “It was nice to race our way up to the front. To come here and do it like that is great. After the last stop, that thing was a rocket ship.”
Hinchcliffe, who also won at Iowa in 2013, made his final pit stop after 225 laps and passed Newgarden with 45 laps remaining, but took the chequered flag under caution after a crash involving Japan’s Takuma Sato and American Ed Carpenter with seven laps remaining.
Second-place Newgarden and third-place Canadian rookie Robert Wickens, hoping for a late restart, went to the pits for new tyres while Hinchcliffe stayed on the track.
But before cars could realign for a restart, Hinchcliffe had taken the victory, American Spencer Pigot was a career-best second and Sato took third.
“It was just the number of laps,” said Hinchcliffe. “By the time you get out of the pits, there weren’t enough laps.”
Reigning IndyCar series champion Newgarden was fourth despite dominating most of the race, but rose to second in the season points chase on 378, 33 behind New Zealand’s Scott Dixon, who was 12th.
“It’s a tough pill to swallow,” said Newgarden. “We had a great car. We just didn’t have it at the end. We just ran out of time.”
“We threw away a podium,” fifth-placed Wickens said.
The 12th of 17 IndyCar season races will be held next Sunday at Toronto.