Collectively, Jimmie Johnson, Tony Stewart and Matt Kenseth have combined to win 10 NASCAR Sprint Cup Series championships and a whopping 145 races, the equivalent of more than four years' worth of races.

This year, though, none of these NASCAR superstars have found Victory Lane yet. Neither has Clint Bowyer, the series runner-up in 2012, nor top-flight drivers like Kasey Kahne, Greg Biffle and Ryan Newman.

While circumstances vary for each individual driver and team, certainly, a common theme resonating among drivers at Charlotte Motor Speedway this week is that they are struggling to come to grips with the new-for-2014 NASCAR aerodynamic package, which among other things eliminated minimum ride heights for cars.

The result, drivers say, is an unusual and paradoxical set of circumstances: Cars that perform well in practice at fast tracks like Charlotte are often terrible, or at least much worse, in the race. The difference being that during practice, cars tend to run by themselves, in clean air, while in the race, there is much more turbulent air caused by the field being in much closer proximity.

The problem has confounded some of the sport's top drivers and teams, especially those who favor loose setups.

"There's a lot of things that have been done to the cars to try and make them drive better in traffic and for me, it's been the opposite: It seems like I get in traffic and they're worse than they've ever been," said three-time series champion Stewart, who is mired at 22nd points with nearly half the Sprint Cup regular season complete.

Stewart is not alone in that sentiment.

"That's definitely what we've been dealing with," said Johnson, the six-time champion. "We develop the balance of a car in practice by ourselves in single-car runs, and then in traffic situations, find that balance is just too uncomfortable to drive. So, we're trying to trade off single-car speed versus how the car handles in traffic. (That) has been kind of our goal."

"We've been really, really good in clean air and practice sessions," added Bowyer. "When you're out there all by yourself we are top of the charts and in the top five or six in race runs and pretty much every mile-and-a-half track and then we start the race and we're in traffic and we can't run anymore. We're out of control and the car is not making good grip and you can't drive the thing."

Brad Keselowski, the 2012 champion, has won a race already this year but admitted he's not a fan of the current direction in aerodynamics and setups.

"If this sport continues to go down that route, cars that are fast in practice week-in and week-out are not gonna win races because it takes something different in practice than what it does in the race," Keselowski said. "That's a hard mindset for me personally and I think it's probably hard for a lot of people within the garage, but it's part of the evolution of the sport."

The flip side of this is that some drivers -- Kevin Harvick and Joey Logano, most notably -- have taken to the new rules package and enjoyed considerable success. And even though he's wrestling with how to find the right setup now, Stewart said NASCAR is attempting to do the right thing.

"It's been a moving target and I think for NASCAR, they're trying things, and I give 'em credit for trying," said Stewart. "You have to try stuff. If you want to make things better, you have to keep trying, and that's something I applaud them for. They're not scared to try things and change it up."