Jimmie Johnson drives through opening to win at Infineon

Reporting from Sonoma, Calif. — A little-known driver from Down Under nearly put one over on NASCAR’S reigning champion.

But just as Australian Marcos Ambrose appeared poised to hold off Jimmie Johnson and win his first Sprint Cup Series race, Ambrose made a fuel-saving move that might be the worst mistake of his racing career.

Johnson exploited the gaffe to win the Toyota/Save Mart 350 at the twisty Infineon Raceway road course tucked into Sonoma wine country, and Ambrose had to settle for sixth.

Ambrose was leading Johnson with fewer than 10 laps left in the 110-lap race when the caution period began, slowing the cars around the 10-turn, 1.99-mile track.

Trying to conserve fuel, Ambrose flipped the engine of his No. 47 Toyota on and off and then stalled the car, allowing several drivers to pass him. Ambrose thought he could return to his lead spot when the race resumed in front of an estimated 90,000.

He was wrong. NASCAR officials determined that Ambrose hadn’t maintained “a reasonable speed” under caution as the rules require. Ambrose had to restart seventh and Johnson held the lead for the last few laps until he took the checkered flag Sunday afternoon — or Monday morning in the island of Tasmania, Ambrose’s home state.

“I’m disappointed,” said Ambrose, 33, an established road racer in his second full year in the Cup series. “I had the motor turned off trying to save a bit of fuel and just had trouble getting it fired again.

“It’s NASCAR’s house and I’ll always play by the rules. I don’t agree with it, I don’t like it, and that’s only because I lost the race.”

Johnson praised his team for putting him in the position to capitalize on Ambrose’s mistake, but added that “I feel bad for him and his team” of JTG/Daugherty Racing. “I’m not sure I would have gotten by him. It was definitely a gift kind of handed to us.”

It was the first road-course win in 17 tries for Johnson who, despite winning the Cup championship the last four years for Hendrick Motorsports, viewed his lack of a road-course victory as a blemish in his career. The other road course on the Cup schedule is in Watkins Glen, N.Y.

Johnson also had been mildly concerned that he’d fallen to sixth in this season’s standings when he arrived in Sonoma. But with Sunday’s win, he jumped to second in the standings, 140 points behind Kevin Harvick.

Harvick, of Richard Childress Racing, finished third to maintain the points lead. Robby Gordon, the veteran road-racing expert from Orange whose one-car team otherwise has struggled this year, was second.

Defending race winner Kasey Kahne was fourth and Jeff Gordon, a record five-time Infineon winner, finished fifth.

As the race neared its end, Johnson said he tried “to put as much pressure on [Ambrose] as I could” in hopes that Ambrose might slip.

Yet, Johnson, who has four wins this year, said Ambrose’s engine shutoff error was “the last type of mistake I would expect to see. I thought maybe he ran out of fuel or had an electrical problem. To see the mistake happen as it did was totally off the wall.”

Chad Knaus, Johnson’s crew chief at Hendrick, said Ambrose “clearly had the best race car today, especially on the short runs. I hate it for those guys.”

The race was filled with the fender-rubbing action typically seen when 3,400-pound stock cars race around a road course. But the biggest crash came as the field was accelerating to take the green flag for a restart on Lap 67.

In the back of the pack, several drivers were caught in a chain-reaction collision as they approached the start-finish line, including Sam Hornish Jr., Martin Truex Jr. and Denny Hamlin, who has won a series-high five races this season.

The wreck required a red-flag period in which the rest of the field was parked for 21 minutes while crews cleaned up the debris.

Another multi-car crash occurred early in the race, collecting Kyle Busch, AJ Allmendinger, Clint Bowyer and Jamie McMurray. Busch fell more than 30 laps behind the leaders while his car was repaired and he finished 39th, but he’s still third in the Cup standings, 141 points behind Harvick.

james.peltz@latimes.com