Dale Earnhardt Jr. says doing practice runs in a simulator is the wave of the future.

AJ Allmendinger might not want to hear that.

As the software continues to improve for providing a reliable reproduction of how a racetrack drives, NASCAR racers can expect to flock to the simulators the three manufacturers have installed in their North Carolina racing headquarters. A simulator uses huge screens, with the seating mechanism in the middle of a dark room, plus an adjacent room for engineers to watch and download data. For Earnhardt, it has become a fairly constant part of his weekly routine.

"When engineers first came into NASCAR, all the racer crew chiefs didn't want to listen to no engineer on their pit box -- and the sim is now the new engineer," Earnhardt said. "It's just a tool some of these guys might not be familiar with. They might look at it as a video game and not real and not realistic.

"But with what iRacing [racing gaming] has done over the years, I saw this coming a mile away. ... It's definitely going to be a useful tool and it's here to stay."

Earnhardt didn't get in the simulator this week to prepare for the 1.99-mile road course at Sonoma Raceway, where practice begins Friday for the race Sunday. But several other drivers did do some prep work for the road course -- the first of only two road-course dates on the 2017 NASCAR Cup schedule -- by using the simulator.

Allmendinger lasted five laps on his first try.

"I did do some first-time-ever sim work a couple of weeks ago -- I ran five laps and I almost puked," Allmendinger said. "Five laps at Sonoma [and] I sweated worse in those five laps in that simulator than I will probably sweat all weekend at Sonoma.

"I puked twice outside, actually. I sat there for a while and the sweats kept going."

Allmendinger isn't the first driver to feel queasy when using the simulator, as the seat moves to simulate how it would feel in the race car, with the setup programmed by the team. Manufacturers get data from cars they bring to tire tests that are able to scan and map the track.

"To me, I drive more on feel," Allmendinger said. "I have to feel it when I get there. There were a couple of small things, I thought, 'OK, that will be interesting to try.' But it's going to be more based on feel when I get in the race car."

Earnhardt said his team often uses a simulator to help determine what adjustments most likely won't work for the base setup the team will bring to the track. That allows team members to focus on the adjustments they think will work best during the limited practice time. Teams are not allowed to do any on-track testing except for going to Goodyear tire tests and the select NASCAR one-car-per-organization open tests.

The simulators, such as this Chevy Racing Loop Simulator, give a visual of specific tracks and then replicate how those tracks feel to the driver. Courtesy of Chevy Racing

Hendrick Motorsports hired Alex Bowman in part to focus on simulator work. Using the grip level in the simulator, he spends several hours trying to determine the tires the team will utilize for the race.

"It's a real tedious process and it's not a lot of fun for Alex, but he gets it close for us," said Earnhardt, a Hendrick driver. "A lot of people aren't quite buying in just yet in the industry, but I like it because we've been able to see it work for us in the sim and on the racetrack.

"It may not do that every week, but Chevy is putting so much money into it, you have to support it. You have to want it to work. If you're a driver, you're like, 'That'll be a great tool if we could make it work, so let's see if it will work.'"

Cup rookies Daniel Suarez and Erik Jones did some simulator work at the Toyota complex last week to get ready for their first races at Sonoma. Darrell "Bubba" Wallace Jr. went to Ford's simulator to prepare for his Cup debut at Pocono. That helped him learn where he needed to shift when he got to the track in Long Pond, Pennsylvania.

"It's helpful," Jones said. "At least it gives you a visual of the track and a few marks and a few shift points and stuff. I can't totally rely on what it's giving you sometimes, but I think for a road course, it's pretty accurate.

"It will definitely at least give me some kind of mark or point to go off of when I get in there and do the real thing."

Ty Dillon said he spends time nearly every Wednesday in the Chevrolet simulator. For the one-car Germain Racing operation, that can be extremely helpful for the team's preparation.

"We go every Wednesday and make laps so I'm as fresh as I can be for being a rookie at some of these places," Dillon said.

Kyle Larson, the points leader in the Monster Energy NASCAR Cup Series, said the simulator probably would help prepare for the road course, but he isn't sold on it overall.

NASCAR driver Chris Buescher demonstrates the Dover Downs Speedway track in the simulator at the Ford Tech Center in Concord, North Carolina. Courtesy of Ford Performance

"I don't do the simulator a whole lot," Larson said. "I still feel like it's got a lot of developing left to do. I have a test in a few weeks ... and then I think we are going to the simulator after that to kind of get the simulator to hopefully drive similar to what it does in real life."

Earnhardt said it won't be necessary for him to use the simulator to prepare for the race next week at Daytona -- the simulator doesn't really simulate the draft -- but he expects to be back in it sooner rather than later.

He pretty much goes when his team says he needs to get a feel for the setups they will bring to the track that weekend.

"They [at the team] book me and tell me when they want me to be in there," Earnhardt said. "We are not going this week [for Sonoma] and we definitely won't do it for Daytona, but we will keep working in that simulator any opportunity we get.

"It's just a free chance to practice. You might learn something, you might not."