Nearly every one has it – and those who don't, well, they will – and they better know how to use it.
No, it's not the latest music download device or an in-car DVD player. It's not even a new safety mechanism.
It is the "secret" that sets apart many teams currently in the top 10 from those on the outside looking in.
It's coil binding, which is a fairly new setup that features a softening of the front suspension. And it will be a part of nearly every team's repertoire this weekend at Dover's fast, high-banked one-mile oval.
NASCAR shortened the rear spoiler on its Nextel Cup cars over the last 18 months by 1¾ inches, resulting in a dramatic loss of downforce to the tail end of the cars and greatly impacting the handling of the cars.
Crew chiefs immediately went to work to find a way to reverse the effects of the rule changes, and it didn't take long to find a solution.
They made the nose of the car drop down as far as it could as the car went into a corner while simultaneously raising or stiffening the rear of the car, causing the car to handle better and run fast both going into and out of a turn.
To do this, crew chiefs softened up the springs on the front end of the car while at the same time stiffening the suspension on the back end. This new and some say radical setup essentially resulted in the front springs becoming solid pieces of metal, bearing little resemblance to their original spring-like shape and performing a function for which they were not originally intended.
The setup primarily is designed to work best as the car enters a corner, but it also has made the cars a handful to drive. One driver who has found it difficult is four-time Cup champion Jeff Gordon, who blames the coil binding setup for his team's struggles over the past couple of seasons.
"One of the biggest reasons we got behind is because we didn't get on top of that setup fast enough," Gordon said. "We started getting softer and softer, but now you got guys that are basically just riding on a spring that coil binds and sets your heights."
Not every driver is as candid as Gordon. When asked about the setup, several drivers denied they even have it on their car – even though their crew chiefs acknowledged that they do – or tried to quash any discussion of it.
"The ones that don't want to talk about it are the ones who haven't got it figured out yet," said Jeff Green, driver of the No. 66 Monte Carlo.
The first use of the softer setup came from DEI's No. 15 team in 2005 with then-driver Michael Waltrip. Crew chief Tony Eury Jr. saw data from a wind tunnel test and discovered that the trick to making the car cut through the air better was to lower the front end and raise the rear.
"We made a decision that year that we weren't going to be going for the championship, so we took advantage of it," Eury said. "Fortunately, we had a driver like Michael who was open-minded to the changes we wanted to make."
It didn't take long for other teams to figure it out and begin to implement the setup on their cars, with the likes of Jimmie Johnson, Tony Stewart and Greg Biffle's teams among those following suit. But other crew chiefs found their drivers having a rough time adapting to the new, slightly more difficult to drive setup.
Eury admits that while the setup can be used nearly every weekend, some weekends teams hit it right and some weekends they don't.
"The team that's getting it right nearly all the time right now is the 9 car," Eury said.
That team, with driver Kasey Kahne, has three wins, three poles and seven top-10 finishes in the first 12 races.
"I don't know what Kenny [crew chief Francis] does; I just know it makes the car go fast," Kahne said. "It doesn't make the car any harder to drive for me. I'm comfortable."
Without a doubt, the key to success with the coil binding setup – which does make the car considerably faster – is making the driver comfortable. For some, the way the car feels as it races into the turn with its nose pointed downward discourages them from pushing the car to its limits.
"The driver has to be comfortable," Gordon said. "You don't just throw super soft springs in there and the car fixes itself. You've got to tie all these different components together to make the driver comfortable."
There are two camps of drivers in the garage – those who like the setup and those who do not. Among those who do well with it are Johnson, Stewart, Biffle, Green, Kevin Harvick and Carl Edwards.
Further complicating the situation is the problem faced by bigger teams that might have one or two drivers who can use the setup while others on the team struggle. Such is the case with Hendrick teammates Johnson and Gordon.
In an effort to find the right setup, crew chiefs will work with different combinations of a) either a soft left spring or a soft right, b) soft springs on both the left and right sides, or c) a left one that compresses before the right one does.
"It has a lot to do with driver preference," Harvick's crew chief Todd Berrier said. "Like it or not, there's a reason why they make 80 percent of the money. They've got to be able to do the job and do it well. They have to be comfortable with the car, or you're not going to go anywhere."
Once a team has found a combination that the driver is comfortable with, they will stick with it week after week.
"You've got to have some consistency in what you do every week, or you'll be chasing your tail and not getting anywhere," Berrier said.
Because the majority of teams in the garage are using the setup, it doesn't fall in the category of a competitive advantage and therefore isn't subject to the scrutiny of NASCAR officials. In fact, not using the setup is, at this point, a competitive disadvantage.
This new setup is just the latest innovation from a garage that is increasingly restricted by NASCAR's rules, though NASCAR can't regulate everything.
"We're going to spend the money in all the areas in which they don't mandate or they're not as strict on," Berrier said.
So what's next?
That's hard to pinpoint.
In racing, many performance improvements aren't as obvious as the soft setup. Most are born from mistakes or from stepping far out on a limb.
But a prerequisite to successfully pushing the envelope is having a talented and open-minded driver to work with.
For a driver, finding that right combination can make a weekend a joy, while missing can make it a nightmare, as Gordon has found out all too often this season.
"One thing that I've learned is that when you hit on the right combination of the springs and the shocks, that's what makes the magic," Gordon said. "Then all of the sudden the car just feels so good and so stuck, and it's not even an issue of adapting."
Veteran motorsports writer Bob Margolis is a Yahoo! Sports NASCAR reporter. Send Bob a question or comment for potential use in a future column or webcast.
