Jimmie Johnson’s demeanor doesn’t match one of a driver out of title contention. Then again, a mishap that took him out could give him a sixth title.

Jimmie Johnson could not have appeared more relaxed had he been snoozing in an easy chair in front of a television tuned to a station that had gone off the air.

Seriously.

The guy is engaged in a pressurized NASCAR Sprint Cup championship showdown. Is it unreasonable to expect him to exhibit a hint of edginess, to deviate ever so slightly from that characteristic “California cool” calm?

Forget it.

And that might be the overriding rationale for believing Johnson retains a viable opportunity in the Ford EcoBoost 400 season finale Sunday to add a sixth Cup title to a resume that rivals those of stock car racing’s legends.

Yes, Brad Keselowski, a rising star at 28, will accelerate past the Ford 400 green flag fortified by the realization he can celebrate his first Cup championship by finishing as far back as 15th even if Johnson runs the perfect race.

But Johnson admitted Thursday, “For whatever reason, I’m at peace with my situation. I don’t want to be in this situation [at a 20-point deficit], but I am strangely optimistic. And I can’t explain why.”

Here’s one explanation: He already has five championships, fewer only than the seven apiece amassed by Richard Petty and the late Dale Earnhardt. Johnson’s large niche in NASCAR history is secure.

Here’s another: The pressure valve has been twisted backwards by the stroke of foul fortune that struck Johnson and the No. 48 Lowe’s Chevolet bunch at Phoenix last week. A blown tire and crash saddled him with the 32nd-place finish that helped stake Keselowski to his 20-point cushion. There’s a limit to what he now can control.

Keselowski’s potential vulnerability to screw-tightening pressure will be microscopically scrutinized beginning with practice and qualifying Friday. But he insisted Thursday that he would be even more energized if Johnson were arriving for the finale nipping at his heels.

People may have expected Keselowski to be doing mental cartwheels after Johnson’s metal-mangling misadventure last week. Not so, Keselowski countered.

“I was really disappointed,” he said. “I wanted the pressure of coming down here having to win the race to win the championship. That’s the type of person I am.

“I want the ball. I want to be on the field on the last play and with the ball thrown to me. I like that pressure. I thrive on it.”

Anyone inclined to dismiss that as bluster or bravado has not been paying attention. The third-generation driver from Rochester Hills, Mich., has bulled his No. 2 Miller Lite Dodge through nine Chase for the Cup races scoring two victories, six other top-10 finishes and no worse than an 11th.

A couple of hours after formal media events Thursday, he strolled back through the writers’ work room and cracked, “You guys OK with the pressure?’’ He got his laughter. He made his point.

A reporter earlier had jokingly capped a question to Keselowski about his seeming immunity to the buildup, “Are you too dumb to know any better?’’

Keselowski howled. “Wow!” he said. “I thought Jimmie was going to be tough!”