He is chasing an elusive goal

For Jimmie Johnson, the NASCAR season finale today will be a coronation or a catastrophe. There is no middle ground for him this year.

In the week since he staked himself to a 63-point lead in the Chase for the Nextel Cup, Johnson has been the heir apparent to stock car racing’s highest championship.

The El Cajon native needs to finish only 12th or better in today’s Ford 400 at Homestead-Miami Speedway to clinch his first title. Four drivers -- Matt Kenseth, Kevin Harvick, Denny Hamlin and Dale Earnhardt Jr. -- still have mathematical chances, but only if Johnson runs into dire trouble.

That’s not expected. The Hendrick Motorsports driver is on a roll, with a victory and four second-place finishes in the last five races. He will start 15th in the 43-car field today, and everyone agrees it’s his Cup to lose.

Johnson, 31, knows how it feels to lose. Each year since reaching the Cup level in 2002, Johnson has nearly won the championship, only to see it slip away. Coming up short again, with a 63-point lead, would be painful.

But Johnson also knows so many things can go wrong in a race, and he is bracing for the worst if it befalls his No. 48 Lowe’s Chevrolet.

“I know that everybody in the garage area will respect what the 48 team has done regardless of whether we have a championship or not,” Johnson said. “I think we have earned that this year.”

At the Homestead race a year ago, for instance, he was chasing Tony Stewart for the title when a tire blew on Johnson’s car, sending him into the wall and leaving him with a 40th-place finish. After the race, Johnson said, “I’ve lived my whole life for this [championship]. But I’ll be back next year.”

Johnson and his crew chief, Chad Knaus, have striven to stay composed and confident this week. Their strategy today is to race hard, be patient and do everything possible to stay out of harm’s way.

That’s the plan Johnson followed a week ago in Phoenix, which earned him a second-place finish behind Harvick and the points lead.

“If we’re in a position to win [the race], great,” Johnson said. “If not, the goal is to be the champion and we want to do the right things to be the champion. I don’t think it would be smart to take unneeded risks.”

Conversely, Johnson can’t play it safe, Knaus said.

“If you have a conservative setup, you’ll go out there and get your butt whipped,” Knaus said. “You have to go out there with the goal that you’re going to run competitive.”

To say Johnson would earn his title is an understatement; he has been on a roller-coaster ride during the 35 races leading to today’s finale.

Johnson opened the year amid controversy, when NASCAR sent Knaus home for bending the rules on the aerodynamics of Johnson’s Chevy before the Daytona 500, the series’ premier race.

But Johnson won the race anyway, and won again three weeks later in Las Vegas. He scored another big victory at the Brickyard race at the Indianapolis Motor Speedway in August, scrambling back from a blown tire that sent him to the rear of the field.

Johnson led in points after 22 of the first 26 races and easily qualified for the 10-race Chase.

Then he hit a slump.

He was 39th in the Chase opener at New Hampshire. At the fourth race at Talladega, Ala., Johnson was poised to win but finished 24th after he was tapped by teammate Brian Vickers on the last lap and went skidding into the infield.

Johnson again fought back with the string of 1-2 finishes over the next five races, a display of tenacity and consistency that reflected his growth as a driver, Knaus said.

“Jimmie has matured an awful lot this year, especially in the last 10 races,” he said.

The Homestead-Miami Speedway is about 25 miles southwest of Miami, a track surrounded mostly by acres of palm-tree nurseries. It’s a 1.5-mile oval with 18- to 20-degree banking in the corners, and today’s race will be 267 laps, or 400 miles.

That’s all that stands between Johnson and the title.

“We’ve overcome adversity and we’ve put ourselves in a position to race for a championship,” Johnson said. “And that’s something I’m very proud of, regardless of the outcome and things I can’t control. I’ll sleep well Sunday night knowing that we tried as hard as we could and we did all that we could.”

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David Gilliland of Riverside starts ninth today, the highest qualifying Ford in the competition.

“I really like the track a lot,” said Gilliland, who was promoted to the Cup series this summer by Robert Yates Racing.

“It reminds me of a short track, Irwindale Speedway, that I grew up racing on.”

james.peltz@latimes.com