Foster maintained his cool through four restarts and was relatively unchallenged throughout all 45 laps around the 1.645-mile, nine-turn temporary street circuit based in the heart of Motor City.
It was the second consecutive victory for the Briton, whose closest rival was HMD Motorsports’ Caio Collett.
“At the start I was just managing the gap.” Foster said. “And then midway through I pulled quite a big gap with him (Collet) thinking he killed his tires.
“But to be fair to him, he came back quite hard in the late stages of the race. It was getting close, but I think we had enough push-to-pass to keep him off.
“And then unfortunately it finished under yellow, which we don't like to see. But happy with the result.”
Collett collected his second consecutive runner-up result, ahead of team-mate Callum Hedge.
Myles Rowe undoubtedly delivered the drive of the day after storming from 19th on the grid to finish fourth in the No. 99 HMD Motorsports with Force Indy entry. Jacob Abel, who started second, finished fifth.
As the field went out for initial pace laps ahead of taking the green flag, championship contender Nolan Siegel couldn’t roll off from his starting spot of seventh due to a broken half-shaft. He managed to return after repairs to his No. 39 HMD Motorsports entry but was four laps down.
Foster was able to get off to a clean start once the green flag waved, gapping the field solidly early on. Meanwhile, Collet moved into second on lap three after a pass on Abel going into Turn 3.
However, the caution came out the following lap after Andretti Global’s rookie Bryce Aron got out of shape on the inside line in Turn 7, with the momentum carrying him into a hard crash with the outside wall.
An extended cleanup time saw the restart on lap 9, with Foster once again getting away cleanly and building a lead of 0.9s by lap 17.
Abel’s spot in third came under threat on lap 20 after Michael d’Orlando, fighting for the chance to continue racing next weekend, attempted a pass in Turn 9.
But the move failed to pay off as the two went side-by-side, with d’Orlando on the outside getting out of shape, with the left-rear lightly tapping the outside wall before spinning around and taking minor damage. He was able to continue on but fell to 17th as Abel maintained third.
The field tightened once again after 25 laps when the yellow flag came out for Jack William Miller temporarily stranded off course in Turn 1. A restart two laps later saw Foster continue the theme of a clean getaway, but Abel continued to be under threat for the final podium spot.
Andretti Global’s Jamie Chadwick was pressing coming out of Turn 3 and going into Turn 4 when she backed off slightly and then suffered a right-rear puncture after getting clipped by the front wing of Yuven Sundaramoorthy. That sent Chadwick and Sundaramoorthy down the running order and out of contention for a top 10.
Abel eventually faded down to fifth following a pass by Callum Hedge and Rowe, who was on the charge after starting 19th.
The front wing damage caught up to Sundaramoorthy, as his Able Motorsports machine brought out the yellow after spinning in Turn 7 on lap 39.
The restart came with five laps to go as Foster was forced to once again defend the top spot heading into Turn 3 and held onto the position as Collet was unable to make a move.
And the caution returned once more with three laps to go after a multi-car crash in Turn 6, which was kickstarted after Andretti Global’s James Roe spun and collected Nolan Allaer (HMD Motorsports) and Niels Koolen (HMD Motorsports).
Despite making a pass for third, Rowe was forced to give up the position as the field reset to the running order prior to the caution.
The race finished under caution, with Foster escorting the field to the checkered flag.
