Tony Stewart figures he's driven more than 20 types of race cars in his career. He's about to try another, and it just might be the ride of his life.

On Tuesday, the two-time NASCAR Cup champion and Formula One star Lewis Hamilton will take turns navigating Watkins Glen International's 3.4-mile long course — Stewart in his No. 14 Chevrolet and Hamilton in his McLaren Mercedes MP4-23.

Then, they'll switch cars in what's dubbed the Mobil 1 Car Swap at The Glen, with Hamilton taking the helm of a non-open-wheel race car for the first time and Stewart hopping in an F1 car.

It promises to be an eye opener for both, but especially Stewart. F1 cars are long, low and sleek, weigh about 1,400 pounds — a ton less than a Cup car — and are designed for road courses. They're also sleekly shaped, go well over 200 mph, and are capable of accelerating from zero to 100 and back to zero in 6 seconds with a V-8 engine that whirrs at 18,000 rpm, about double what Stewart is used to.

"I'm somewhat familiar a little bit with what kind of downforce they have, but I've never run one at a road course," said Stewart, who has a record five Cup wins on The Glen's 2.4-mile short course used by NASCAR. "It's going to be one of those things you can talk about all day long, but you're not going to fully understand it until you actually sit in the car and drive it."

Stewart, who won an IndyCar Series title before leaving for NASCAR in 1999, is counting the minutes.

"The further my career went along, the more that you wanted to have opportunities to drive everything," said Stewart, who has raced on the long course that includes the famed Boot section, competing in a Grand-Am Rolex Series race six years ago. "Obviously, having the opportunity to race in the IndyCar Series and knowing that the final step of that would be Formula One, it was always a goal ... to say at some point we'd get an opportunity to drive one. Once I stopped racing in the IRL full time and started NASCAR full time, I thought that opportunity would never come about."

Watkins Glen bills itself as the soul of American road racing, and its storied open-wheel history includes Formula One's United States Grand Prix, which ended a 20-year run in 1980.

This year marks the 50th anniversary of The Glen's inaugural F1 race, so the timing was perfect for WGI president Michael Printup, who has a soft spot in his heart for Formula One.

"It's not a money thing. It's a fun thing. It's going to be phenomenal," said Printup, a spectator at the 1975 U.S. Grand Prix won by Niki Lauda. "I made a promise to the community — you will see a Formula One car at this track. I didn't say series, but I did make a hard promise. I got an email the other day, and it said, 'You kept your word. You got your car.'"

Four-time Cup champion Jeff Gordon and former F1 star Juan Pablo Montoya, a Cup regular now, did a similar swap nearly eight years ago to the day at Indianapolis Motor Speedway. That planted the seed.

"We were just talking about when Jeff and Juan did it at Indianapolis," Stewart said of a meeting with Mobil, a sponsor for Stewart-Haas Racing. "They took that ball and ran with it. The next thing we knew they had talked to McLaren and basically had set this all up for us. I'm really excited."

Printup said there was a rumor last summer that a swap might happen with Sam Hornish and Hamilton. Nothing materialized, although Hamilton's engineers made a visit to WGI.

Rumor became fact in December, and the parties involved made the trip to The Glen in the dead of winter.

"We had a covert meeting," Printup said. "I told them they couldn't wear anything because people around here are fanatic. I said, 'Don't wear gear. There will be spies on us in a minute.'"

After the meeting, a track inspection was needed to start planning with a TV production crew that's producing a 30-minute special.

"We came up here, and we had a blizzard of a storm. We actually had to plow the track, which is the worst thing you can do to a racetrack because the snow actually insulates the track from frost-heaving," Printup said. "They wanted to get on the track — the Mobil 1, McLaren and Formula One people. They wanted to be able to film it so they could get a feel."

Formula One hasn't raced in the U.S. since 2007 after an eight-year run at Indianapolis Motor Speedway. Printup has no illusions about luring F1 back to The Glen — the cost would be too great and the series already has plans to begin racing next year at a new track in Texas. But just hearing the distinctive roar of one of those engines again at The Glen will be music to more than a few ears.

"It's free, so I think we'll get a lot of people," Printup said, hoping for a walkup crowd of 7,000 or more. "But a lot's going to play on the weather and, 'Am I going to play hooky today and go out to The Glen?'"

The forecast is calling for a 40-percent chance of rain.