FONTANA, Calif. --- Jimmie Johnson overpowered the field Sunday night in the NASCAR Sprint Cup race at Auto Club Speedway, grabbing his third victory of the season.

The two-time reigning Cup champion was easily the class of the field in the Pepsi 500, leading 227 of the 250 laps on the 2-mile oval.

He won the race at the former California Speedway for the second year in a row and again gave notice to points leader Kyle Busch and series runner-up Carl Edwards -- the two hottest drivers in the series coming into this race -- that he remains a serious contender for a third consecutive title.

Runner-up Greg Biffle had the next best car throughout the race, but he couldn't keep up with Johnson's No. 48 Chevrolet, finishing more than 2 seconds behind the winner.

Everything was cool at the start of the race -- or at least considerably cooler than a year ago.

At the 5 p.m. start local time, the temperature was 85 degrees at Auto Club Speedway, 22 degrees below the stifling heat at the beginning of the 2007 race.

This time, the temperature was expected to drop into the mid 70s late in the race, to the relief of the drivers who had to endure the scorching heat last year.

"This is one of the toughest tracks that we come to as far as that. The heat is so bad here," Denny Hamlin said, adding that it makes the speedway one of the toughest on the drivers.

"In the summer, the track gets really greasy, the seats get really hot.

"This is probably the No. 2 physically demanding track (behind Pocono) that we go to, especially with this being 500 miles. This is one that you have to stay hydrated for your entire week leading up to it. Even though it goes into the night it's still very, very hot."

Northern California native Jeff Gordon said the heat is just part of the deal for drivers, who get their hot-weather routine down to a science.

"Not quite as hot as it was last year," he said heading into the race. "It's just something that you have to get used to. It's just a part of the conditioning."

Johnson has been helping out with some housing that has nothing to do with transmissions while he's in Southern California.

"We're out here right now building four homes for Habitat for Humanity and just yesterday, we had a ceremony where I handed out the first set of keys over to a family. That was pretty cool, man," Johnson, a native of El Cajon, Calif., said.