Marco Andretti led a 1-2 for his father’s team in a day of 40mph wind and intermittent rain at Indianapolis Motor Speedway.
The third-generation driver, who almost won the Indy 500 as a rookie in 2006, set his best time in the morning session, the #27 Andretti Autosport-Honda lapping the famed 2.5-mile course in 40.2816s, an average of 223.427mph.
Teammate and 2014 winner of the “500” Ryan Hunter-Reay was second fastest, 0.25s off, having set his best lap in the afternoon.
Fastest of the Chevrolet runners was current IndyCar points leader Simon Pagenaud who set a 221mph lap in the #22 Team Penske entry to edge Josef Newgarden’s Ed Carpenter Racing car by just three-hundredths of a second.
Carlos Munoz backed up his teammates’ performance with fifth for Andretti, showing no ill effects from his two shunts at Phoenix International Raceway last weekend.
Tony Kanaan was top Ganassi-Chevrolet car, as the 2013 Indy winner was sixth, despite clocking only 16 laps. Behind him was Penske's three-time winner Helio Castroneves, two-time Indy polesitter Ed Carpenter – who turned the most laps, at 51– Will Power, Scott Dixon, Juan Montoya and Graham Rahal.
The purpose of today’s test was to assess the various configurations of the Chevrolet and Honda superspeedway aerodynamic bodywork kits.
"We ran through quite a few different combinations as part of the aero kit configuration test," said Bill Pappas, IndyCar’s VP of competition, race engineering.
"The conditions weren't ideal, but we did get a lot of information to go over and look through over the next couple of days to get ready for the month of May."