Drivers and teams most likely won't have a great idea of how their cars will race in the 2018 NASCAR All-Star Race until ... the race.
There's a good reason: They haven't received the actual front air ducts their cars will use.
The teams will be handed pieces Friday in the NASCAR Cup garage that they will have to bolt onto their cars for the first time. They haven't been given exact dimensions of the air ducts, which will take air through the front fender and channel it outside the car before it gets to the front tires.
That aero package, combined with a restrictor plate, should make for a different All-Star Race.
Here's the who, what and why to questions about Saturday's event at Charlotte Motor Speedway (8 p.m. ET, FS1).
Who is in it?
The race is open to 2017-18 race winners (no matter if they are full time or not) as long as their wins didn't have any rules violations, and any past All-Star Race winner or past Cup champion if they are full time.
Those qualifications put 17 drivers in the field.
Winners from 2017-18: Kurt Busch (first 2017 race won: Daytona), Brad Keselowski (Atlanta), Martin Truex Jr. (Las Vegas), Ryan Newman (Phoenix), Kyle Larson (California), Jimmie Johnson (Texas), Ricky Stenhouse Jr. (Talladega), Austin Dillon (Charlotte), Ryan Blaney (Pocono), Kevin Harvick (Sonoma), Denny Hamlin (New Hampshire), Kasey Kahne (Indianapolis), Kyle Busch (Pocono), Matt Kenseth (Phoenix), Clint Bowyer (Martinsville, 2018) and Joey Logano (Talladega, 2018).
Past All-Star Race winner: Jamie McMurray (2014).
There will be four more spots left in the field for a total of 21 cars -- the winners of each of the three stages of the Open plus the driver with the highest fan vote. To be eligible for the fan vote, a driver must have been running at the finish of the Open and have a car that is able to race for the all-star event.
How do they qualify?
The qualifying for the last-chance "Open" race is two rounds of group qualifying, with the first round lasting 15 minutes and the second round (top-8 from first round) being five minutes. It starts at 6:05 p.m. ET Friday and leads into All-Star Race qualifying.
The All-Star Race qualifying is three laps with a four-tire pit stop (no pit-road speed). Drivers get 5-second penalties for loose lug nuts or other violations.
What is the format for the Open?
The Open has three stages: 20 laps, 20 laps and 10 laps. A driver who wins a stage advances to the All-Star Race (and can immediately drop out of the Open). There will be overtime at the end of the first two stages (if needed), and the race will end with two consecutive laps under green with as many attempts as needed for a green-white-checkered finish.
What is the format for the All-Star Race?
It is four stages: 30 laps, 20 laps, 20 laps and 10 laps. Only green-flag laps count in the final stage. No mandatory pit stops this year (normal stage-break procedures). Overtime rules are in effect for the end of the first three stages, and the race will end with two consecutive laps under green with as many attempts as needed with a green-white-checkered finish.
What is the aero package?
The package is similar to the one used by Xfinity Series teams at Indianapolis in 2017 (and will be used at Indianapolis, Michigan and Pocono for those cars this year).
In addition to the front aero ducts, there will be the bigger 2014 splitter, a spoiler that is 8 inches high over the final foot of the spoiler width and a restrictor plate with holes of seven-eighths of an inch in diameter. The typical spoiler for most races is 2.375 inches high.
Have teams tested the package?
Not as much as they likely would have wanted. They did their best to try to run simulation with this package, but they haven't had the actual parts and pieces to take to the wind tunnel.
What is the goal of the aero package?
The goal is to have drafting and three-wide racing, much like at Daytona International Speedway, with the 20th-place driver running as well as the first-place driver. Drivers expect they won't have to lift off the throttle throughout the lap.
What if it is a good race -- can those rules be implemented this year?
No. The charter agreements forbid NASCAR from making significant aerodynamic changes during the season except for safety reasons. Also, it is quite possible NASCAR gets a false barometer because teams haven't been able to science out these cars.
As Brad Keselowski put it last month: "It's extremely diminishing returns beyond the All-Star Race, but I do respect the fact that there is an idea to get one good race out of [it] and they're using it, so I can respect that, but anything beyond that will be pure garbage."
Here's Jimmie Johnson's thoughts: "In talking to the Xfinity guys that ran the package at Indy, I think Indy might serve that package better with the long straightaways to be able to take advantage of the way the aero works on the car, but let's try. I mean, why not? There's really nothing to lose. It might not be the package we love and want, but I'm sure it will get us a step closer, and we'll continue to evolve."
What is the winner's purse?
The winner earns $1 million. Or at least that is what the team gets. It is up to the team owner to distribute the money to the team members, depending on how their contracts read.