The Associated Press

FONTANA, Calif. - Somehow, Greg Biffle kept his car pointed in the right direction long enough to take the checkered flag.

''I lost all the rear grip there with three (laps) to go,'' Biffle said as he celebrated his victory Sunday in the Auto Club 500. ''I just barely touched the wall, skinned it, two or three times there at the end and I was just able to keep it under me.

''We had the fastest car on the racetrack, but just not right there at the end.''

Biffle, who won the 2004 season finale in November, ran strong throughout the 250-lap race on California Speedway's 2-mile oval, taking the lead for good on lap 228 and building an advantage just big enough to hold off a last-ditch effort by runner-up Jimmie Johnson in the second NASCAR Nextel Cup race of the season.

''Man, I saw Biffle hitting the wall and sideways a few times there at the end and I could hardly believe he got to the end,'' said Johnson, who passed Kurt Busch for second and nearly caught Biffle on the final lap. ''But he had a strong car and he did a really good job.''

Biffle, who finally was able to figure out the right combination in the first test of NASCAR's new aerodynamic rules, twice came back from as far down as 30th.

''I had to pass every car and I earned it,'' the winner said. ''That's why I freed the car up so much is because I was back in that traffic. Then, when I got back out front it was so dang loose that I couldn't drive it.''

Roush Racing had a great day, with Biffle winning his fourth Cup race, reigning series champion Busch finishing third and taking the season points lead, Carl Edwards fifth and Mark Martin seventh.

Matt Kenseth also ran in the top 10 most of the day, but fell off the lead lap on lap 234 with a flat tire and wound up 26th.

The key moment of the race came on lap 218 when Busch, running second, and Biffle, in fifth, stayed on track while leader Kevin Harvick and most of the other contenders pitted for tires during the last of seven caution periods.

Busch, faked toward the pits before driving back onto the track, taking the lead, with Biffle just behind. Biffle was able to drive into the top spot seven laps after the green flag waved for the final time.

''It wasn't a really hard decision,'' Biffle said about staying on track. ''We only had seven laps on those tires. Those Goodyear tires they brought here are a really good compound and it takes five laps for them to come in, so we only had a two-lap advantage by pitting.''

Johnson was one of several drivers who did pit for four new tires on the last stop and he charged back from 10th, finishing just 0.230 seconds - about six car-lengths - behind the winning Ford Taurus.

''We should have been able to win that race,'' Johnson said. ''I got tangled up with some slower cars and it knocked me up in the marbles and I lost too much ground.''

Busch was disappointed, too.

''You get so close, you just want to be able to capitalize,'' he said. ''I ran so hard at the beginning (of the last stint), I smoked my tires and Johnson got us there at the end.''

Jamie McMurray finished fourth, followed by Edwards and Harvick.

This was the first race in which the Cup cars ran with shortened rear spoilers and softer tires, an effort by NASCAR to make the racing more competitive and allow more passing by taking away downforce and putting more responsibility in the hands of the drivers.

It also was the first time that the teams have had to start the race with NASCAR holding the cars from the end of qualifying on Saturday until Sunday morning and allowing only minor adjustments before the start.

''It was real hard to find the balance of the car out there at times,'' said Busch, off to a strong start after finishing second to Jeff Gordon a week ago in the season-opening Daytona 500. ''I wished they'd have tried it more in the Busch Series before they brought it to Cup.''

Busch moved into the series lead by five points over Johnson, with Martin 39 behind the leader.

Johnson said he didn't find the new rules to be a big problem.

''The cars definitely had some movement in traffic, but it didn't bother me much all day long,'' added Johnson, last year's series runner-up and the favorite to win this year's title.

Joe Nemechek appeared to have the strongest car for much of the race, leading a race-high 63 laps before his engine blew. Nemechek was one of five drivers using Hendrick Motorsports engines, including Gordon, who had problems during the race.

Gordon, the defending champion in this race and a three-time winner in California, was still in contention when he lost a cylinder late in the race. He wound up 30th.