Fontana, CA - Ryan Hunter-Reay became the first American driver to win the IZOD IndyCar Series championship after finishing fourth in Saturday night's 500-mile season-ending race at Auto Club Speedway.

Hunter-Reay benefited from Will Power's accident in the early going and then made a late-race charge to the front to clinch his first IndyCar title by just three points over Power.

"This hasn't sunk in yet," Hunter-Reay said. "I just drove 500 miles like it was for my life. I can't believe we are IndyCar champions. My dream has come true, and this is unbelievable."

Power entered the season-finale with a 17-point lead over Hunter-Reay, but Power lost control and spun out before backing it into the wall on lap 55. His Team Penske crew feverishly worked to repair the car, and he returned to the track 70 laps later. But the Australian managed to only run a dozen laps before taking the car back to the garage and retiring from the event.

"There were definitely times that it looked hopeful," Power said. "Full credit to my guys for getting the car out and doing those 12 laps. It gave us a couple of points. Hunter-Reay is a very deserving champion and a real fighter. He's probably as far as all around drivers one of the best in the series."

With Power finishing 24th, Hunter-Reay needed to finish sixth or better to clinch the title. Hunter-Reay had his share of difficulties throughout the week in Southern California, as he wrecked during Wednesday's test session at this two-mile oval. He had to start 22nd in the 26-car field after receiving a 10-grid spot penalty for an unapproved engine change.

"We were struggling all week, and I didn't want to let anyone really know about it that much," he said. "We were really in the woods."

Hunter-Reay and Power had been running within two positions of each other prior to Power's accident.

Power qualified third on Friday but had to start 13th after he was penalized for an engine change as well. He dropped back to 21st within the first three laps. Hunter-Reay was nearly caught up in Power's accident.

"(Power) was right next to me, and I saw him lose it, so I bet it was pretty close," Hunter-Reay said. "He was joking around that he would take me out if I was next to him. He almost did."

After Alex Tagliani made contact with the wall in turn four with 20 laps remaining, Hunter-Reay moved into the top-five. An accident involving Tony Kanaan with 11 laps to go forced IndyCar race officials to briefly halt the race. It setup a six-lap shootout to the finish.

Hunter-Reay ran in third for the final restart but lost the position to Scott Dixon. Ed Carpenter and Dario Franchitti, who had won the series title in each of the last three years, were battling for the lead in the closing laps. Carpenter moved ahead of Franchitti to take the top spot just before Takuma Sato crashed on the final lap, ending the race under caution.

Carpenter picked up his second career IndyCar win, while Franchitti and his Chip Ganassi Racing teammate, Dixon, finished second and third, respectively.

"Dario is the best to race with," Carpenter said. "We were really good early and then kind of struggled through the middle, but the team made great adjustments on the car late, and we got dialed back in."

Carpenter led a race-high 62 laps. His first win in the series came on Oct. 2, 2011, a race that would turn out to be the season-finale. The scheduled season-ending race at Las Vegas was canceled after a horrifying 15-car crash that claimed the life of Dan Wheldon occurred in the opening laps.

Hunter-Reay gave Michael Andretti his fourth IndyCar championship as a team owner. Andretti's other titles came with Tony Kanaan (2004), Wheldon (2005) and Franchitti (2007).

"(Hunter-Reay) did a great job, and it was a total team effort," Andretti said. "He just did a hell of a job there at the end. When he needs to step it up, he steps it up. He got us a championship, and I'm really proud of him."

Following the completion of Friday's qualifying, Andretti Autosport announced that Hunter-Reay had signed a two-year contract extension with the team.

Sam Hornish Jr. was the last American to win the IndyCar title, doing so in 2006. Hornish is now a competitor in the NASCAR Sprint Cup and Nationwide Series, driving for Roger Penske's organization.

Power finished runner-up in the championship standings for the third year in a row. While the road/street courses have been his strong suit, Power has struggled on the ovals throughout his IndyCar career. His best finish in the five oval races this season was eighth, which came in June at Texas. He also finished 28th (Indianapolis), 12th (Milwaukee) and 23rd (Iowa).

"As I look back at the season, I had three crashes on the ovals, and that was massive hits in the points," he said.

It was also the third straight year that Power has been involved in an incident either on the track or on pit road during the last race of the season.

Hunter-Reay scored a series-high four wins this season, including three in a row. His victories came on the ovals at Milwaukee and Iowa and then the street circuits in Toronto and Baltimore. He had trailed Power by 36 points prior to Baltimore.