"Shake and bake. That's what we're going to do," Hamilton said Tuesday as he climbed behind the wheel of Stewart's No. 14 Chevrolet at Watkins Glen International to prepare for a day like no other in his racing career.
And that's exactly what the two star drivers did in an event 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.
Not even a cool, drizzly day that forced them to use rain tires at the storied road course could dampen their spirits.
Hamilton was first to go out for setup laps in the McLaren Mercedes MP4-23 that he drove to the F1 title in 2009. He wowed the crowd with a burnout as he left the pits and did only two laps as the surface slowly began to dry.
Stewart followed in his Chevrolet, going five laps as he tried to get accustomed to navigating the famed mile-long Boot section of the layout. Stewart has a record five Cup victories at The Glen, but NASCAR uses the 2.4-mile short course that eliminates the Boot.
Then came the swap.
"I never in a million years thought I'd have the opportunity to drive a NASCAR," said Hamilton, who isn't accustomed to standard shift and admitted to being nervous. "I don't know what to expect. I know in NASCAR, you blow engines. We very rarely do that nowadays."
Stewart, who was fitted for his new ride Monday, was curious, as well.
"I think I've raced one time in my career in the wet," he said. "That was about five years ago. This ought to be a very interesting day, for sure. I got to run in the simulator yesterday quite a bit, but it didn't have a rain program."
Hamilton wowed the crowd, spinning the tires of Stewart's Chevy as he left pit road and turned six laps. The track was slowly drying after a morning rain, and when he was finished, Hamilton did an impressive burnout as the crowd roared.
"I just feel like a kid. It's good to feel like a kid again. It's one of the coolest things I've done outside of racing Formula One," said Hamilton, who crashed early in Sunday's rainswept F1 race in Montreal and finished last. "The competitive side of (racing) is so serious. After a tough weekend, I was worried even this morning."
The smoke from the burnout made Stewart grin from ear to ear, even if it was one of his own cars.
"The good part is when you see somebody doing a burnout like that, you know they're having a good time," he said. "That was icing on the cake."
An F1 car can go from zero to 100 mph and back to zero in 6 seconds, can reach speeds over 220, can turn 18,000 rpm, and weighs a ton more than a Cup car. No problem for Stewart, though, who won an IndyCar Series title before moving to NASCAR in 1999.
After a shaky departure from the pits, Stewart got up to speed fast in the McLaren Mercedes MP4-23 despite not having driven an open-wheel car in a decade. Among his four laps, he turned a fast one of 1 minute, 42 seconds in tricky conditions.
That was 8 seconds faster than Hamilton's best setup lap, which Hamilton ran on a much wetter surface. The track record for the long course is 1:28.597 at 136.935 mph, set by IndyCar's Ryan Briscoe in 2009.
"I couldn't even get it up high enough in the revs to get it to actually pull away in first gear. I kept having to reset it," Stewart said. "I kept trying to tell myself, just get on the gas a little bit. As a competitor, you want to go out and find the limit. At the same time, you realize that if you make a mistake, the penalty for that mistake is going to be pretty harsh, so you may back it off a little bit just to enjoy the experience.
"Once we got rolling though, it was unbelievable. It's just amazing what the capabilities of the car are. I told the guys on pit road that it's probably going to make my crew chief a little more stressed during the weekends now because I'm going to want it to handle like that all the time. That was truly the experience of a lifetime."
The event was a triumph for Watkins Glen president Michael Printup, who counts F1 as a passion. The Glen hosted F1's U.S. Grand Prix from 1961-80. And for one day, that distinctive engine roar that once woke campers up on race day echoed through the hallowed turns of the famed course.
Heck, the event, which was free, attracted 8,000-10,000 fans.
"I can't get rid of my goosebumps and my chills," Printup said. "It was amazing, and it was amazing to have these fans out here. For me, personally, I haven't come down from Cloud Nine. And I think I'm going to stay there at least for the rest of the day."