Tony Kanaan took an early advantage over the rest of the field, setting the fastest time of the 75-minute practice session on Friday morning ahead of this weekend's Chevrolet Dual in Detroit presented by Quicken Loans.
The Ganassi driver set a best lap of 1:16.2931s (110.888mph) on the 2.35-mile, 14-turn street circuit on Belle Isle, putting him two tenths of a second ahead of his rookie team mate Sage Karam.
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The brace of Ganassis were pursued by a trio of Penskes, with reigning IndyCar Series champion Will Power third fastest ahead of Simon Pagenaud and Helio Castroneves.
Juan Pablo Montoya - the fourth member of the Penske contingent, and the winner of the 99th running of the Indianapolis 500 last weekend - was only tenth fastest for the session but still within a second of Kanaan's top time.
Only one Honda-powered driver made it into the top ten, with AJ Foyt Racing's Takuma Sato finishing the practice in ninth place. Sato holds the existing track qualifying lap record for the current Belle Isle circuit of 1:16.1371s (111.115 mph) set 12 months ago.
The Honda contingent were largely occupied with getting used to the new feel of their cars after implementing the latest change mandated by IndyCar to their aerodynamic bodywork kits. Series officials have told the Japanese manufacturer to remove the outer vertical wall of the front wing assembly end fence, attached flaps and strakes.
"We've been very cautious of any change that would make the car a challenge to drive and spoke with the manufacturer beforehand to make sure that wasn't the case,” explained IndyCar's vice president of technology Will Phillips. "The manufacturer understood our motivation and supported this action."
Teams have installed a patch where the vertical wall had been attached to the front wing assembly. Meanwhile Chevrolet has introduced a winglet on the top of each sidepod for added downforce which should help performance on the street circuit this weekend.
There were a number of brief stoppages during Friday's practice, with the first red flag coming out 15 minutes in to the session for CFH Racing's Josef Newgarden spinning out, and there was a second red flag for debris in turn 11 at the half-hour mark.
A few minutes later there was another break following separate incidents for Dale Coyne Racing's Rodolfo Gonzalez and Rahal Letterman Lanigan Racing's Graham Rahal. Sage Karam also triggered a stoppage with a little under 15 minutes remaining when he turned around.
The drivers now move straight on to qualifying for race 1 which takes place in the afternoon at 3.40pm ET (8.40pm BST) which follows the usual three-round elimination format for street and road courses.
The drivers get a second half-hour warm-up practice on Saturday morning at 8.55am ET (1.55pm BST) before the first race of the weekend scheduled to start at 3.50pm ET (8.50pm BST).
Sunday sees a second qualifying scheduled at 11.25am ET (4.25pm BST). In this case, car will be split into two groups each of which will have 12 minutes to set their best lap, which will decide their starting positions. Race 2 again gets underway at 3.50pm ET (8.50pm BST) later in the day.
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