Felipe Drugovich was left "surprised by the speed" after his maiden IndyCar test with Chip Ganassi Racing last Monday.
The Brazilian, who serves as the reserve driver for Aston Martin’s Formula 1 team, received his first taste of Indy car machinery at Barber Motorsports Park, logging 129 laps and posting a best time of 1m07.631s.
Drugovich, who combined his F1 reserve duties with a drive in the LMP2 class of the European Le Mans Series this term, told Autosport: "The driving style is very different.
"I was surprised by the speed, but at the same time, it was very different from what I thought it would be. I imagined it would be very similar to an F2 car and even the driving style is not that different, but the feeling the car gives you is extremely different from anything I have ever driven.
"The car has a different geometry, the tyres they use are really good, with a softer sidewall and you feel the car moving under you a lot more.
"I think it was a very good experience for me. In terms of times, I did well, I drove well, I showed what I could do. Even though it is a test with a rookie driver in the series, they use it to test the car itself, because even there the tests are very limited, so we tested a lot of things for the team in terms of setup and they really liked the feedback, so I am very happy with the results."
Ganassi's now-three-time IndyCar champion Alex Palou set the fastest qualifying lap when the series visited the Alabama circuit earlier in the season with a 1m05.5862s, though that was without the hybrid power unit that was introduced mid-season.
While power is boosted with the new unit, it has also added weight to the car and in comparison, Palou set a time just inside the 1m08s mark in a pre-season test with the hybrid units fitted.
"We had a reference," said Drugovich.
"For those who don't know, the Barber round this year was held before they had upgraded the car, which is the hybrid part, so this hybrid in the car added almost 80 kilos, and that made it almost one second slower.
"So, you can't compare the race times, but they had done a test before that, in the pre-season, with the hybrid already on that track and the reference they had I was being faster. It's difficult to compare this because of the track conditions and everything else, especially because they were just starting out with the hybrid and, logically, they have improved since then.
"Since the morning I've already been very close to the ideal time, using the first set of tyres. In the end, I started faster, so I showed the team that I'm ready. It's my first contact with the car and I'm not 100% [adapted] to single-seaters again, so I'm sure that the longer I stay in this car or any other single-seater, I'll continue to improve and get back to my peak.
"Looking ahead to next year, I think IndyCar is one of the opportunities - we're studying it. They changed the regulations, so each team will have a maximum of three cars.
"This test was planned since last year. It didn't happen before because of scheduling clashes but it happened this year. It was a really cool opportunity for me to get involved in the American world of motorsports.
"I had already done something with Cadillac and Action Express [at the 24 Hours of Le Mans], but now I actually tested an IndyCar, which was really good."