SONOMA, Calif. (AP) -- Josef Newgarden rushed through the doors on to the championship stage with an American flag draped around his shoulders. He felt silly, he said, like a boxer at a title fight.
Fitting for IndyCar's newest champion.
Newgarden won his first IndyCar championship by closing out the best year of his career as the top driver at Team Penske. He turned in a nearly flawless performance Sunday at Sonoma Raceway to prevent his three Penske teammates -- as well as four-time champion Scott Dixon -- from taking the title.
Penske driver Simon Pagenaud used pit strategy to win the caution-free race, but Newgarden finished second to take the title by 13 points.
Newgarden is only the second American in 11 years to win the IndyCar title, joining 2012 champion Ryan Hunter-Reay.
The Tennessee driver held off Dixon, as well as teammates Pagenaud, Will Power and Helio Castroneves to win the championship. Of the five drivers mathematically eligible to win the title in the finale, four came from Penske.
Pagenaud won the race in a last gasp effort to defend the IndyCar title he won last year for Penske. Although his strategy was different from his teammates, it put Pagenaud out front after his final stop.
Newgarden tried to catch him, was briefly aggressive as he attempted to reclaim the lead, then had to back off and think about the bigger picture.
"I was using my natural instincts. I was trying to get Pagenaud there because that's what I normally do, I try to win the race whenever possible," Newgarden said. "I tried to get him, but I also tried not to do anything dumb for the team. This has been a team effort."
Power finished third in the race, Dixon was fourth and Castroneves fifth in what might have been his final full season in IndyCar. Castroneves, in his 20th season, is likely being moved to Penske's sports car program next year.
"Let's see what's going to happen," Castroneves said. "Right now let's celebrate the championship. I feel like I am part of it."
It was an uphill fight for Dixon, in a Honda for Chip Ganassi Racing, and he didn't have the same pace as the Penske cars all weekend. That meant Dixon would have to rely on an aggressive strategy to have a shot, but Newgarden and the Penske drivers were far too quick in their Chevrolets.
When Dixon tried to pit off sequence, he felt Castroneves copied the strategy in an effort to help Newgarden.
"He was just a massive roadblock," Dixon said about Castroneves. "It was circumstance. Once we got clear track, we were able to hunt them down."
The final standings went Newgarden, Pagenaud, Dixon, Castroneves and Power. Chevrolet drivers have won every championship but one since the engine-supplier returned to IndyCar in 2012, and the brand has beaten Honda every year for the manufacturer championship.
Penske has won back-to-back titles in IndyCar. Pagenaud won the championship last year, when Penske drivers went 1-2-3 in the final standings. Despite that success, Penske grabbed Newgarden when he became a free agent and booted Indianapolis 500 winner Juan Pablo Montoya from his ride to make room for the young driver.
It was a cutthroat business decision, but resulted in a 15th IndyCar title for Penske. The organization has 30 championships in various forms of motorsports.
"We saw how good he was when we were racing against him," Penske said. "It's a team effort here, a great thing for our team."
For Newgarden, it completes a rapid ascension to the top of the series.
The 26-year-old is in just his sixth IndyCar season, and the opportunity this year to drive Penske equipment separated him from the pack. Newgarden scored career highs in wins, podiums, laps led, and, most important, the final standings.
But, he had appeared to have coughed the championship away two weeks ago when he crashed exiting pit road at Watkins Glen. It allowed Dixon to slice Newgarden's points lead to just three points, and it made Dixon the favorite because he's so savvy in these situations.
Only Penske, with the four chances at the title, arrived in Sonoma completely dialed in and its four cars were the class of the field all weekend. The effort was led by Newgarden, who broke the track record three different times in qualifying while winning the first pole of his career.
If he was rattled by Dixon, or anyone else, he never let it show.