Tony Stewart wins Kobalt Tools 400 at Las Vegas Motor Speedway

One year ago, Tony Stewart had a dominant car at Las Vegas Motor Speedway only to see victory slip away on pit-stop strategy that backfired.

“We had the fastest thing on the planet,” a crestfallen Stewart said then, “and we just gave it away.”

Not so Sunday, when Stewart was just as fast and the reigning NASCAR Sprint Cup Series champion vindicated last year’s setback by winning the Kobalt Tools 400, his first win at Las Vegas.

“Just an awesome day,” Stewart said. “Our car was so, so strong today on the restarts. That was a big key in holding these guys off.”

Jimmie Johnson, the five-time champion who was driving a backup No. 48 Chevrolet after crashing his primary car in practice, finished second and Greg Biffle was third in front of an estimated 150,000.

Stewart’s teammate Ryan Newman was fourth and defending race winner Carl Edwards finished fifth.

Stewart repeatedly shot ahead on restarts following several late caution periods in the 267-lap race, leaving Johnson, Biffle and the others helpless to catch his No. 14 Chevrolet.

“It was clear the 14 car had more power than we did,” said Biffle, who drives a Roush Fenway Racing Ford. “It’s been a long time since I’ve seen a car that fast.”

Stewart, whose nickname is “Smoke,” is known for starting slowly each season. But winning the third race this season was an early reminder of how he won five of the 10 races in NASCAR’s Chase for the Cup playoff last year to earn his third title.

“The spring historically has not been our strong suit,” Stewart said. But he said erasing another track from his winless list was more satisfying.

There are now two tracks on the Cup schedule where the 40-year-old Stewart hasn’t won: Darlington (S.C.) Raceway and Kentucky Speedway.

“That’s what makes today so special, not so much the time of year we’re getting it, just the fact we finally got this one,” he said.

Sunday’s victory also was Stewart’s first since he hired crew chief Steve Addington this year to replace Darian Grubb.

Grubb was released from Stewart-Haas Racing — the team Stewart co-owns — despite helping Stewart to last year’s crown.

Grubb’s new driver, Denny Hamlin of Joe Gibbs Racing, won last week’s race in Phoenix. In the same race, Stewart finished 22nd after he switched off his engine during a caution period and could not immediately get the car restarted.

Stewart rebounded Sunday by leading a race-high 127 laps even though the field repeatedly was bunched together under the late caution periods, giving his rivals another shot at the front.

“You hate having to reset [the field] like that, knowing for the first three laps you had to be spot on and not let them take advantage,” Stewart said.

On one restart, when Stewart was third, he made a daring move to the inside and swept past the two cars in front before they had reached Turn 1.

After the last restart with four laps left, Johnson, the only four-time winner at Las Vegas, tried to get to Stewart’s bumper but couldn’t close the gap.

“If I could have got to his outside on the restart, I think I had a chance,” Johnson said, but “they were awfully strong.”

james.peltz@latimes.com