DAYTONA BEACH, Fla. -- The new "shark fins" on the back of the Sprint Cup cars at Daytona International Speedway this season have nothing to do with the nearby Atlantic Ocean, or as a tribute to the cars that ran here in NASCAR's early years.

Instead, they're a deceptively simple solution to an increasingly complex problem: how to keep the current chassis from getting airborne in a crash, like Ryan Newman's wild flight at Talladega last fall.

NASCAR's new managing director of competition, John Darby, said finding a solution to that problem was the primary focus of off-season wind tunnel testing, starting with the 2 1/2-inch tall rear window strip, already mandated at restrictor-plate tracks.

"It came from a couple of days in the wind tunnel, looking at different options, different ideas that we had had, ... trying to do a better job of keeping the cars on the ground," Darby said. "Part of that was going back and looking through all of our old notes and things that we had tested. The strip that has been on the rear window for quite some time, and going back through the history of things we've added to the cars, it was pretty attractive. So it was a matter of 'if that worked pretty good, then maybe, is a little bigger better?' "

According to the initial tests, it was. But NASCAR's engineering staff began to think about taking it one additional step.

"The first step we made was to add an extra inch to the rear window strip," Darby said. "And we saw some gains. It wasn't huge. It wasn't enough to make us stop testing or anything like it.

"But through that process, we started understanding what that strip does, and that's to slow the rotation of the cars as well as pack some more air on that rear window. Our engineers said, 'What would happen if we continued this strip down the trunk lid?' It not only had the same effects but the two enhanced each other and we made some pretty substantial gains by adding that strip."

So how exactly does the new trunk fin work?

"If you ride down the highway and you put your hand out the window and you hold your hand in the direction the car is traveling, there's not a lot of resistance," Darby said. "But turn your hand sidewise and it'll come back and slap you in the forehead. It's a very similar effect."

"If you picture the strip on the car, and you're going down the straightaway, it really doesn't have that much effect. But as the car starts to spin and the strip now sees the air pressure, it does two things. It slows the rotation of the car down, and as the air comes across it, it packs air on top of the trunk lid to help push the car back to the ground before it lifts." (Continued)