The offseason renovation and repaving of Kentucky Speedway changed the conversation when NASCAR Sprint Cup Series teams returned Thursday.

Drivers remarked about the track's new character - a grippy, smooth surface featuring two unique ends that make it unlike any other 1.5-mile track on the circuit. The offseason work narrowed Turns 1 and 2 from 74 feet to 56 feet and increased the banking from 14 to 17 degrees in those turns. The banking in Turns 3 and 4 remains at 14 degrees.

"It lends itself to compromises with the race car drivers, techniques and car setups, and all those things that tend to open up the box to allow for better racing," two-time Quaker State 400 winner Brad Keselowski said. "Whenever there are those discrepancies, I think that's when you see mistakes and when you see strengths and weaknesses that vary from car to car and driver to driver.  I think that's a really good thing for our sport, so I'm interested to see how that is going to play out this weekend."

Joe Gibbs Racing teammates Carl Edwards and Kyle Busch, the two-time and defending Quaker State 400 winner, led the only practice held Thursday. Keselowski and Kasey Kahne both brushed the wall during the 85-minute session.

Edwards logged the fastest lap (186.451 mph) in his No. 19 Joe Gibbs Racing Toyota and led all drivers with 51 total laps completed. Martin Truex Jr., Denny Hamlin and Jimmie Johnson also posted laps that put them in the top five.

"We scuffed a bunch of tires. That's what we did," Edwards said. "While we're doing that, I'm just looking at what are the little nuances of the track. Where are the bumps? Where is the grip level different? Exactly where is the speed?

"This track is difficult. The difference between Turns 1 and 2 and 3 and 4 is a bigger difference than any of the mile and a halfs that we go to. It's huge. Determining how you're going to balance the car and where to be aggressive and how loose you need to be here and there, it's kind of hard to figure it out."

The repaved and reconfigured surface isn't the only change this weekend. Sprint Cup teams are running a lower downforce package and Goodyear brought a different right-side tire from what was used during an organizational test held June 13-14.

"This is a big unknown with the new surface, the tires, the package," Edwards said. "That's the kind of racing that is fun to go do."

Teams will have two more opportunities to practice on Friday before qualifying for Saturday's race. The practices are scheduled at 11 a.m. and 1:30 p.m. Qualifying is set for 6:45 p.m.