Takuma Sato and Will Power repeated their afternoon form with the top two times in IndyCar's fourth and final three-hour session at ISM Raceway, while four-time champion Scott Dixon had a rare spin and clipped the wall.
Tony Kanaan’s AJ Foyt Racing-Chevrolet sat at the top of the speed chart for much of the session, but with 75 minutes to go, Power – who had been at the bottom of the times doing long runs – put a fresh set of tires on the #12 Penske-Chevrolet and sprang to the top. Less than 10mins later though, the Rahal Letterman Lanigan Racing-Honda of Sato deposed him.
Their times would hold to the end of the session, as would Kanaan’s in third.
"The open test was very successful, I would say," Sato said. "Lots of things done and lots of things to be tried, and I think over the course of two days we learned a lot. Great car, definitely more exercise for the drivers, definitely busier with low downforce.
"We did qualifying simulations and race traffic runs. I think the Rahal Letterman Lanigan team is really strong, so I'm really looking forward to two more road course tests and hopefully we'll be ready for St. Pete."
Power said: "Really enjoying this car; the 2018 car is awesome. Our #12 Verizon Chevy's been pretty good the whole time. We're really in a good window, I feel like… [but] so are a lot of people, by the look of it."
In the final 40mins, following a track inspection, the action got frantic as drivers practiced running in traffic. Dixon’s #9 Chip Ganassi Racing-Honda appeared to get too close to a car in front and spun, making light contact with the Turn 1 wall.
Said Dixon: "It was our second or third lap out of the pits. A couple of the Andretti cars got by and were a little bit slower. I got low in [Turns] 1 and 2, touched the throttle and had a bit of a run and lost the rear. Kind of late in the corner, but just touched with the rear and bent the left-rear suspension.”
It was the same spot where Foyt’s other driver, the rookie Matheus Leist, had whitewalled his tires earlier today, and had spun yesterday. The young Brazilian still wasn’t done yet, brushing the Turn 4 wall twice in the last half hour. He nonetheless finished the session in the top 12.
Fourth fastest time went to reigning champion Josef Newgarden, in the #1 Penske-Chevy, while Marco Andretti and Alexander Rossi were fifth and sixth for Andretti Autosport-Honda. Only the top five breached the 189mph threshold.
Dixon’s best time was stout enough to beat last year’s Phoenix winner, Simon Pagenaud, while Spencer Pigot looked the most competitive he’d been throughout the two days of testing, putting the #21 Ed Carpenter Racing-Chevy into ninth.
Dale Coyne Racing’s Pietro Fittipaldi was a highly impressive 10th, and top rookie.
The Carlin Racing-Chevrolets made another solid impression, winding up 14th and 16th, but the Schmidt Peterson Motorsports-Honda duo of James Hinchcliffe and Robert Wickens were at the bottom of the speed charts.