This year’s IndyCar championship comes down to MAVTV 500 in Fontana

This year’s IndyCar championship was Helio Castroneves’ to lose, and he’s nearly done just that.

The Brazilian driver had a 49-point lead in the title standings with three races left in the season, only to have a disastrous double-header in Houston two weeks ago because of mechanical woes.

So now Castroneves is 25 points behind Scott Dixon as the Izod IndyCar Series comes to Auto Club Speedway in Fontana for the season finale Saturday night.

If Dixon finishes fifth or better in the MAVTV 500, the New Zealander will capture his third series title, regardless of how Castroneves finishes.

And if that happens, Castroneves — a three-time winner of the series’ crown-jewel Indianapolis 500 — will again be denied his first IndyCar championship.

“At this point I feel that I have nothing to lose,” said Castroneves, 38, who drives for Team Penske. “There is no pressure, to be honest. You just go for it.”

The team was “extremely happy with the performance of the car two weeks ago [at a test] in Fontana, and we just hope we continue with that,” he said.

IndyCar last year returned to the two-mile Auto Club Speedway oval, where the cars reach speeds well in excess of 200 mph, after a seven-year absence.

The 2012 finale was a thrilling race won by Ed Carpenter on a warm mid-September evening, and the championship wasn’t decided until the final laps, when Ryan Hunter-Reay’s fourth-place finish enabled him to win the title by only three points over Castroneves’ teammate Will Power.

IndyCar this year moved the race back a month to enjoy cooler conditions, and the green flag is scheduled for 5:50 p.m. The drivers will have two practices and their qualifying session Friday before racing Saturday.

The sport’s second-level series, Firestone Indy Lights, will race at Fontana earlier Saturday afternoon.

Dixon, a reserved personality, drives for Target Chip Ganassi Racing and has four wins this season, including the first race of the Houston double-header. The 33-year-old driver said his goal at Fontana was “to go there setting our sights on winning. If we can achieve that, then it makes the championship story just sort of unfold.”

But he added that Castroneves is a “very accomplished driver” with a “very accomplished team,” and that “I think it’s going to come down to the last lap.”

Dixon’s teammate is Dario Franchitti, a four-time champion who suffered two spinal fractures and a broken right ankle when his car crashed into a catch fence in the second Houston race Oct. 6. Franchitti will be replaced Saturday night by veteran driver Alex Tagliani.

Bonus pay

Dixon and Tony Kanaan have extra incentive to win Saturday because a victory would earn them a $250,000 bonus.

Golfer Fuzzy Zoeller’s vodka company, which sponsors Carpenter, initially offered a bonus of $1 million to any driver who could win all three of the series’ long-distance races this year: The Indianapolis 500, the Pocono Indy 400 and the MAVTV 500.

Kanaan won at Indy and Dixon won at Pocono, so there was no $1-million payoff. However, Zoeller’s contest still provides a $250,000 bonus to a driver who wins two of the three races.

james.peltz@latimes.com

Twitter: @PeltzLATimes

MAVTV 500 IndyCar race

Where: Auto Club Speedway, Fontana

When: Saturday, 5:50 p.m.

Length: 500 miles, 250 laps

Track size: Two-mile oval

Defending winner: Ed Carpenter

Also Friday: Two practices (10:45 a.m., 6:05 p.m.), qualifying (2:15 p.m.)

Also Saturday: Firestone Indy Lights race/50 laps (2:30 p.m.)