AVONDALE, Ariz. -- With passing at a premium, particularly at the front of the field, Greg Biffle was forced to ride the roller coaster during Sunday's Checker Auto Parts 500.

Because of dueling pit strategies and a series of green-flag stops, the No. 16 Ford was a solid top-five car at times, then fell to as far back as 26th before things righted themselves at the end.

"I was up and down throughout the day," Biffle said. "Track position, pit sequencing, you're in front, you're in back. Those cars are just so hard to pass that track position is just so important. We had to race our way from around sixth or seventh on that last stint on two tires to get up in there."

In addition, Biffle and crew chief Greg Erwin found a few adjustments that brought the car to life late in the running.

"I struggled all day with it not turning and then loose in," Biffle said. "We just kept doing air pressure and wedge and all kinds of things.

"We got onto something at the end I wish we would have done at the beginning instead and felt we may have won this thing if we would have been on to what made the car go earlier in the race."

Starting seventh on the Lap 274 restart, Biffle had one of the fastest cars on the track -- but ran out of time before he could chase down eventual winner Jimmie Johnson.

"We just kept working on it and I wish we would have had better track position where we could have got a crack at [Johnson] because we definitely had a faster car," Biffle said. "But there at the end he just had too much track position on us.

"I thank Matt Kenseth for pulling over. He pulled over and let me have a crack at him. We just needed Jimmie to make a little mistake and we would have been on him, but those guys are pretty good at not making mistakes."

Biffle said much of the problem with passing lies with the Car of Tomorrow. For one thing, all of the cars are running equal speeds. And if you get a run on another car, Biffle said the handling goes away.

"The old car, I felt like you'd get a car length behind a guy or a couple car lengths at a track like this, but now you get three car lengths behind a guy and it just kind of loses it," Biffle said. "You don't really sense it, you just feel like the tire is giving up a little bit and that's just because you're so on the edge anyway and it's just all you can do, and now you're kind of stuck three cars back."

At the same time, Biffle said you can make passes without much difficulty -- if everything is right.

'[When] you run up to the top and get it turned and get the gas, then all of a sudden you just run right by the guy on one straightaway if you get a run," Biffle said. "Diamond the corner and get a lot of straightaway speed or something. It's like it's aero-tight early because it makes a big hole in the air, so to speak, because the car is bigger, but you don't really notice it."