Andretti Autosport will take an even bigger step forward for the 2019 IndyCar season, predicts championship runner-up Alexander Rossi.
The ex-Formula 1 driver and 2016 Indianapolis 500 winner produced Andretti's strongest title bid since Ryan Hunter-Reay's '12 crown this year and finished runner-up to Ganassi's five-time champion Scott Dixon.
Rossi dominated the Long Beach, Mid-Ohio and Pocono rounds to score his three 2018 wins.
He believes a "pretty big step forward" on road courses was the strongest element, highlighting a potential one-two at Portland before full course yellows interfered with his and Ryan Hunter-Reay's strategies, plus Hunter-Reay being "on a different planet" as he dominated the season finale at Sonoma.
"The cars have been strong really from day one, but particularly on road courses from Mid-Ohio onwards," Rossi said.
"We definitely found something then. We've been able to kind of carry that forward, not just be a flash in the pan.
"It's been progress that's been quantifiable and repeatable. That's a huge testament to the effort that the team puts in.
"I have every expectation that they're going to continue this development process this off-season and we're going to come back in 2019 even a bigger step ahead than we were this year."
Rossi, Hunter-Reay and Marco Andretti finished second, fourth and ninth in the 2018 standings, having been seventh, ninth and 12th a year earlier.
"It's an awesome 2018, and something that we all can be very proud of at Andretti," Rossi added.
"Obviously having three cars in the top nine in the final points is amazing, a huge improvement from where we've been in the past.
"It's really a good overall year for the team, especially the second half.
"We'll take the positives and try to improve on the negatives and see where we can end up next year."