Updated

Thirty-one Sprint Cup Series teams day opening Daytona 500.

During the morning single-car session, Hendrick Motorsports driver and three- time Daytona 500 winner Jeff Gordon topped the speed charts with a lap at 192.773 mph. Paul Menard was second fastest at 192.369 mph, followed by Kurt Busch, who is making his debut with Phoenix Racing after being released from Penske Racing at the end of the 2011 season.

Ricky Stenhouse Jr. was fourth and Juan Pablo Montoya fifth. Stenhouse Jr., the reigning Nationwide Series champion, has landed a ride for the Daytona 500 in Roush Fenway Racing's No.6 Ford.

Teams are mainly familiarizing themselves with NASCAR's new rules package for next month's race at Daytona. A number of revisions have been made to the Sprint Cup cars for restrictor-plate racing at Daytona and Talladega Superspeedway this year, including a smaller capacity in both the radiators and overflow tank.

In addition, the radiator inlet will be moved up closer into the front center bumper area. The springs on the cars will be softer and the rear spoiler smaller. The restrictor plate has been modified to 1/64 inch larger than the plate size used for last year's Daytona 500.

"I'm glad they [NASCAR] opened up the cars a little bit and gave us a bigger plate," said 2004 Daytona 500 winner Dale Earnhardt Jr. "I think the changes they made are really good, and I can feel that I'm going around the corners faster than I have been in the last couple of years, which is good."

Earnhardt Jr. was 11th quickest (191.388 mph) in the opening session. He won the pole for last year's Daytona 500 with a lap at 186.089 mph.

NASCAR is hoping to minimize and perhaps eliminate two-car drafts, which has become an unpopular style of racing at restrictor-plate tracks. The sanctioning body is also considering banning communications between drivers on their car radios during the race in effort to break up the two-car tandems.

Earnhardt Jr. doesn't think NASCAR's rule of ceasing communication between drivers while on the racetrack will make that much of a difference.

"I don't think it will be a big deal," he said. "Pretty much everybody is working with teammates anyway. I don't think their going to limit that, so I don't think it will be any big deal. When we first started tandem drafting, you might ended up working with somebody outside of your company. But then everybody sort of got a little strict on who they're going to work with and how they're going to do it, and they stuck with that plan for the entire race."

Some two-car drafting took place during the afternoon hours on day one at Daytona.

The test session will also allow teams with new drivers this year to get familiar with each other. Running a limited Sprint Cup schedule this season, beginning with the Daytona 500, Danica Patrick is getting more acquainted with her crew chief, Greg Zipadelli, and the crew members of her No.10 Stewart-Haas Racing team.

"Today it's just run on our own and seeing how fast we can get the car to go," Patrick said. "I think [Friday] we'll work on bump drafting. I heard Tony [Stewart] say he's going to let someone else do it first with the new rear spoiler and springs, so that's fine with me. I said that I think I want to be the one getting pushed, so I don't be the one who takes out my boss [Stewart]. That would be bad."

Last month, Zipadelli was named as the new competition director for Tony Stewart's multi-car organization. Zipadelli had served as crew chief for Stewart (1999-2008) and Joey Logano (2009-2011) at Joe Gibbs Racing.

As of now, Patrick is not guaranteed a starting position in the Daytona 500, but Stewart, the 2011 Sprint Cup driver/owner champion, could give his owner points to Patrick to ensure her a spot in the race.

"I think we're still trying to figure that equation out," Stewart said. "The good thing is looking on the sheet today the car seems to have good speed right off the bat. I've got the utmost confidence that even in the worst-case scenario that we've got the right driver that can get this car in the race with no problem.

"We're working through that and trying to get it finalized and figuring out what are options are to make sure that we give her the best opportunity to get into the Daytona 500 and get her all the experience that we can get her."