Tony Stewart, Kurt Busch, Brian Vickers and Greg Biffle have been running from Tuesday with the new device during a Goodyear tyre test at the mile-and-a-half oval, giving positive feedback about the new feel of the car.
Initial impressions point at the car shifting the balance slightly towards more front-end grip, although there did not seem to be a dramatic change to its handling on single-car runs.
"It didn't seem to be a big balance change, which was good," said two-time Cup champion Stewart. "That means you won't have to reinvent the wheel necessarily. It was a balance shift, but it wasn't a big balance shift."
Former Cup champion Kurt Busch echoed Stewart's impressions and expects the spoiler to improve racing once the device is used in a race for the first time.
"With the spoiler on, the car had a looser feel to it," Busch said. "The car was turning better and it felt like the car was sliding a bit more. What we have to do is ultimately put together a better package for drivers to drive on the track, which would create more side-by-side excitement for our fans to enjoy."
Roush Fenway's Biffle said the handling of the car reminded him of the old specification, which used to run a spoiler too. He believes more drag has been added to the car with the spoiler, given its four-inch profile and 70-degree angle
"It drove a little bit different on corner exit than the wing did," Biffle said. "I don't want to jump to conclusions, but it may have had a little feel like the old car in some scenarios. You can tell it has some more drag because they made it a little bit bigger and wider."
Red Bull's Vickers expects the new spoiler to improve the handling of the car while running in dirty air, as he believes the rear wing to be less efficient in that condition.
"Theoretically, from what I've been told, the difference between the two is that the spoiler is better in traffic," said Vickers. "The spoiler is going to be more efficient in dirty air and a wing will be more efficient in clean air.
"Once you get in a lot of turbulence, the spoiler's not going to lose a lot of efficiency while a wing really will."
The first official test with the device for all teams will take place at Charlotte Motor Speedway on 23-24 March before it the spoiler is raced for the first time.
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