Kurt Busch was about 30 minutes late for his interview when my phone rang.
"I was just making a run," the 2004 Sprint Cup champion and current points leader (tied with Tony Stewart) said apologetically. "It's hard to know in drag racing when you get to go out."
Yes, drag racing.
While most of his fellow Cup drivers are taking advantage of an off weekend, Busch is competing in the Pro Stock class of the NHRA Gatornationals in Gainesville, Fla. He was in Charlotte for barely 24 hours after finishing ninth Sunday in Las Vegas before leaving for the Sunshine State to practice.
"I just really have been falling in love with the drag racing world," Busch said.
Busch isn't considering leaving the Cup world for the NHRA any time soon. He still has 10 to 15 more competitive years left in a stock car.
This isn't something Busch is doing just to knock an item off his bucket list, either, however. If scheduling allows, he will enter the Mile-High Nationals in Denver on his next off weekend.
But this is something Busch can see himself doing well into his 50s and maybe 60s after his NASCAR career is over. As 61-year-old John Force proved last year by winning his 15th Funny Car championship, this isn't necessarily a young man's sport.
"Yeah, that's crossed my mind," Busch admitted. "I love NASCAR, but if there is going to be a young kid that pops me out of my seat in the Cup world, there might be an opportunity to go drag racing afterwards."
Nobody is going to knock Busch out of his seat at Penske Racing the way he's driving these days. He easily could have won the Daytona 500, where he finished fifth after winning the Budweiser Shootout and one of the two qualifying races. He followed that with an eighth place at Phoenix after starting on the outside pole and a ninth at Vegas despite a spinout.
He's showing the consistency that led to his first title seven years ago and has made him a top-10 driver five times since entering the series full time in 2001.
"If I could find any ounce of this speed [in drag racing] and put it in my Cup car, we'd be lapping the field," Busch said with a laugh.
You can hear the excitement in his voice as he talks about this weekend. The adrenaline rush he gets going close to 210 mph in under seven seconds with a g-force of 3 is like nothing he experiences in NASCAR. He relishes the opportunity to one day top 300 mph in a Top Fuel dragster.
"It's insane," Busch said of the speeds achieved in a nitro-fueled machine. "Let's just say I have to walk before I can run."
You can hear an excitement in his voice that you seldom hear in his Cup world. He talks of meeting legendary driver Bob Glidden the way one of his own biggest fans would talk about meeting him.
"I'm looking at him, and I'm like, 'This is Bob Glidden, I know it is. He has a Ford hat on and everything,'" said Busch, his voice raising an octave or two. "He was [like], 'Son, that was a cool run. If you can drive those stock cars, you can run these straight-liners.'
"I was like, 'No way! That was Bob Glidden.' And that was just at a test session."
The NHRA should be just as excited, maybe more, to see Busch in its series. Having a former Cup champion compete brings attention and fans to the sport that it normally doesn't get.
"Oh, yeah," said Allen Johnson, Busch's teammate this weekend and one of the favorites in the Pro Stock series. "He'll be lined up as long as he wants, signing autographs. We'll use all that to our advantage that we can."
In that respect, Busch going drag racing does compare to Danica Patrick entering the world of NASCAR. You can't put a price on the exposure the sport gets from having the top female from IndyCar in its show. The NHRA can only dream that Busch will draw similar attention in Gainesville.
"We're hoping the hell he does well," four-time Pro Stock world champion Greg Anderson said of Busch. "I don't know how many of the Top Fuel guys know about it, but they're going to learn it's pretty big for the sport."
Anderson is a big reason Busch is exchanging left turns for a straight line this weekend. Let's digress.
In 2007, a curious Busch drove to Concord, N.C., for opening night of zMax Dragway. At one point in the evening, Anderson approached the stock car driver and asked whether he could make a few runs down the quarter-mile track in his Dodge Viper.
Anderson promptly burned the clutch out of Busch's car.
"I'm like, 'Wait a minute! This is my personal car!'" Busch recalled with a laugh. "He was, 'Oh, no way! I know people that can get you some parts.' I said I know people, too. I told him I'll get my car fixed, then I'm going to drag racing school and when I'm ready, I'll drive your Pro Stock car."
Not long after that, Busch's wife, Eva, surprised him with a spot in Roy Hill's Drag Racing School. After some intense training during which no preferential treatment was given because of what he did in NASCAR, Busch found himself entered in last year's Super Gas series in Gainesville with a Mopar-powered 1970 Dodge Challenger he bought on eBay for $15,000.
Unfortunately, rain plagued the event to the point that Busch didn't get proper practice, and he made only two runs before being eliminated Sunday morning when his machine sputtered on takeoff.
That didn't discourage Busch. It only intensified his interest.
He spent most of his free time in the NASCAR offseason getting ready for this week's event. He teamed with Johnson, who helped him get his Pro Stock license with a best run of 6.576 seconds (201.43 mph) at Bradenton, Fla.
To put that into perspective, that would have qualified Busch 11th in the 16-car field he hopes to make Sunday.
"He'll have a motor in his [Dodge Challenger] just as good as my car," Johnson said. "I can qualify if I make good runs. He can, too."
I never dreamed he would go through with it. I never dreamed one day he would want to come here and show me how it's done.
”-- Four-time Pro Stock champ
"He very possibly could surprise a few people," Anderson said. "I never dreamed he would go through with it. I never dreamed one day he would want to come here and show me how it's done."
Which brings us to the question, which is tougher -- driving a stock car or a drag car? In a stock car, if you miss the setup early, you still have an entire race to get it right. Or if you spin out early or make a mistake on pit road, you can make up a lap and still have a chance to win.
In drag racing, if you miss by one hundred-thousandth of a second you're going home. You have about five minutes between the time you roll onto the grid, do a burnout, stage the car and take off to get everything right. Miss one shift and you're done.
"So the high that you're on as a driver is at an all-time high for me in drag racing," Busch said.
So which is tougher? Anderson can't say for sure, but he tried his luck in a stock car at Bristol Motor Speedway in a celebrity all-star race in 2009. It didn't turn out nearly as well as what Busch has experienced in a dragster.
"I slapped the s--- out of that wall," Anderson said. "The guy that owned that car wasn't too proud of me. That's why I am so impressed with what Kurt is doing. I give him all the credit in the world for stepping out of his comfort zone. It's a challenge.
"The safe route is to turn down the opportunity and stay in your comfort zone. Whether he succeeds or fails, he's a true racer."
That ultimately is what it's all about for Busch. He's driving this weekend for the same reason brother Kyle drives everything with a wheel on it in a NASCAR weekend.
He's doing it with the blessing of team owner Roger Penske, whose only concern is that he be safe and not ruin his chances of another Cup title.
"It's just that I'm a car guy and I love to challenge myself with many facets of auto racing," Busch said. "This is a challenge. I know it's above my head, but it's been a burning desire through my mind to go and conquer this."
One gets the feeling he will.
David Newton covers NASCAR for ESPN.com. He can be reached at firstname.lastname@example.org.