DAYTONA BEACH, Fla. -- Preseason Thunder testing at Daytona International Speedway ended a day early for about a third of 35 teams after a Friday crash involved 12 cars in a pack.
Marcos Ambrose spun into the field after a push from Dale Earnhardt Jr., precipitating the crash. He collected Sprint Cup champion Brad Keselowski, Jamie McMurray, Kasey Kahne, Jeff Gordon, Kyle Busch, Joey Logano, Regan Smith, Greg Biffle, Carl Edwards and Aric Almirola.
Earnhardt's car made it through unscathed, but all the other drivers except for Edwards, Biffle and Busch began packing for home because they had no backup.
Edwards has a backup and the damage on the cars of Biffle and Busch wasn't significant.
Because parts and pieces have taken longer than expected to get NASCAR's approval, many teams are behind on production of the new "Gen 6" car. Hendrick Motorsports had only four approved decklids needed for cars to test at Daytona.
Some team officials were wondering if they would be able to field a car for the Jan. 17-18 test at Charlotte Motor Speedway, but their immediate concern was time lost preparing for next month's Daytona 500.
"We definitely had a list of things we were wanting to accomplish tomorrow," Gordon said, referring to Saturday's third and final day of testing. "So that's unfortunate."
However NASCAR vice president of competition Robin Pemberton isn't concerned that some teams won't have enough cars to test at Charlotte or be ready for Speedweeks at Daytona in mid-February.
He said 100 deck lids -- the only common piece for the entire season -- already have been distributed and NASCAR will begin issuing 50 each week beginning on the 18th.
Pemberton said part of NASCAR's focus that led to the wreck was to eliminate pushing with bumpers and encourage pushing with air as was the case before the COT.
"We haven't seen anything that didn't look like it wasn't in our favor to put on the grid,'' he said.
Earnhardt said the crash was the result of less downforce and the front bumper of his Chevrolet not matching up with the back bumper of Ambrose's Ford.
Earnhardt and most of the other drivers agreed the crash marked the end of the two-car draft that NASCAR worked so hard to eliminate with the old car at this test a year ago.
"I felt like Marcus was backing up on me in [turns] 1 and 2 to get a run down the back," Earnhardt said as he explained what happened. "I was going to give him a push down the back straightaway to get the lead. Our cars didn't match up very well. I got him hooked into the fence.
"The roll bar was just at the right place where his car sat right up on top of that. I sort of had him going down the back straightaway like a forklift. It was a big mess."
Earnhardt and others said drafting will return to the way it was prior to the old car -- introduced in 2007 -- in which the bumpers matched perfectly for pushing all the way around the track.
Gordon said drivers really shouldn't consider pushing with the new package, especially in the corners.
"Unfortunately, that's kind of the last bit of momentum that you need to sometimes make a pass or make a lane move," the four-time champion said. "It's something that's going to have to be dealt with very carefully.
"Most of the time, you need to stay away from it."
Earnhardt and Edwards said it ultimately will make for better racing because it will put the control back in the hands of the drivers.
Unfortunately, many of the teams lost a much-needed day of practice discovering that.
"The sport is rewinding," Keselowski said. "That is the important thing to say. The sport advanced to the two-car tandem three or four years ago and there were certain things you could do then that you couldn't do in the past without wrecking. Now the rules package is back to where we were in the early 2000's, when the fans enjoyed the racing better."