Rossi, who scored his first roadcourse IndyCar win and pole position in last September’s penultimate round of the season at Watkins Glen, described his first test of the 2018 aerokit as “very productive” but with the caveat that track conditions were near-perfect. His #27 Andretti Autosport-Honda completed around 130 laps over the last two days and he said the new bodywork had a very noticeable effect on the car’s straightline performance.

“It feels like we’ve had a big power boost,” he told Motorsport.com, “which is great because that’s what every racecar driver wants.

“I noticed it halfway down the straights – in fourth, fifth, sixth gear, it really wants to keep on pulling whereas before, you’d get to fourth and the speed gains you had afterward were so gradual it didn’t feel like you were going any quicker. With this car, that’s definitely not the case any more; it feels how a proper racecar should feel like, like we’ve had a power increase.

“But because of that higher approach speed and less downforce, the braking zone is a challenge – that’s the big area that everyone’s talked about. You’ve got to work around to minimize the effect of losing that, and we came into this test with assumptions of what it would be like but not really knowing. Leaving the track, I’m cautiously optimistic. We came out of the box with a decent package but with a long test list and we got through a lot of that. We understand a lot more about what we need and what we’re looking for.

“But the caution is that it was also one of those perfect days at Sebring – overcast, cool, the sun wasn’t beating down – so we haven’t seen the worst of it yet. Hopefully when we come back [Jan. 24th] it will be warmer and more realistic of the IndyCar championship in the summer. We had all four of the Andretti cars out there, plus the two Ganassi cars, and the track came in quite quick even though it rained quite heavily yesterday morning and then rained again overnight.”

2018 car feels like a trimmed out previous-gen IndyCar

Rossi, who raced in Europe from 2009 to 2015, and took wins in GP3, Formula Renault 3.5 and GP2, said he had been expecting the new kit to transform what was originally called the Dallara DW12 into “more of a European-type racecar” and the fact that it hasn’t done that has both a positive and negative.

“I was expecting to need a big driving-style change but no, it’s like a very loose IndyCar from the past couple of years,” he said. “You lose high-speed capability and braking capability but the general balance is the same. You’re working more because the car’s sliding more, but you’re working in different areas.

“For me, I suppose it’s a double-edged sword, because I thought it would have the type of handling that took me back to my roots, as it were, open-wheel racecars in Europe; but on the other hand, I’m happy it’s not super-random, and that the two years of learning I’ve had in IndyCar so far haven’t been thrown out the window. The handling balance and idiosyncrasies that I’ve had to learn still transferred.”

Asked if he felt the car suited his preferred driving style, Rossi said: “Well you’re right, I’ve always preferred a car’s handling to be ‘on the nose’, and that’s how this car is in the initial phases of the corner and you have to be very comfortable with that, and very precise with the way your hands and feet work together. So that’s good.

“But at different stages of the corner it’s still a 1600lb IndyCar with massive rear tires that overpower the front, so there is still a phase where you struggle with understeer like you did with the old car. It’s kind of a two-prong car now, if you will. There’ll be guys who struggle with that initial instability and there’ll be other guys that are fine with the instability but then struggle as the speed comes off, the front wing becomes less effective and it transitions to understeer.

“You can obviously adjust that depending on how much of a penalty you want to take under braking and on corner entry. I mean, you can make it so that the car doesn’t understeer at all, but then you’re going to have your hands full everywhere else. So it’s about finding the trade-off between the two.”

Regarding traction out of the corners, Rossi said his views were colored by the favorable track conditions.

“For me, it’s hard to tell how much that has changed because, like I said, the track conditions were so good,” he said, “but I’d imagine that it will be more difficult than last year’s car in terms of putting the power down when the track is more greasy and you’re near the end of tire life. You’ll see guys pedaling it on corner-exit a lot more than last year.”

Working at a disadvantage to other teams

With Schmidt Peterson Motorsport and Team Penske starting the testing of the 2018 IndyCar last July for Honda and Chevrolet respectively, and Chip Ganassi Racing and Ed Carpenter Racing being the second teams to test for their respective manufacturers, Rossi admitted that Andretti Autosport does feel at a disadvantage to only begin testing in January.

“It’s a big mountain for us to climb, even on a four-car team” he said. “I’ve got to admit it was a big surprise to realize the difference in number of test days between ourselves and some of the other teams. And it’s also left us in the situation where it’s really hard to tell where we stand compared with the others. This was a private test, only one of the manufacturers was here.

“We’ve got another day at Sebring on Jan. 24, then the IndyCar open test at Phoenix [Feb. 9-10], and then another day at Sebring, and that’s it for us until first practice at St. Petersburg. That really is tough, you know?

“I think it’s obvious Andretti Autosport has done a really good job back at the shop in terms of understanding the car – we rolled off really well. But some other teams have had five to eight more days on track compared with us, and that’s an advantage for sure. We had a really good day-and-a-half at Sebring, although, like I say, we need to be cautious because the conditions were so perfect. But the other teams have been at Road America, Mid-Ohio, Indy, Phoenix, Texas and so on, so I still feel we’re at a pretty big disadvantage in terms of understanding the car.”

Rossi will run the #27 on his car this year, while teammate Marco Andretti switches to the #98 Andretti-Herta car, as he continues with Bryan Herta as his strategist.