INDIANAPOLIS -- With straightaways only 50 feet wide and turns banked at fewer than 10 degrees, negotiating the venerable Indianapolis Motor Speedway's ribbon-like asphalt at speed is already the perfect recipe for single-file racing. But add to that the turbulence from running directly behind another car, and it compounds the problem of passing.

Greg Biffle felt it first-hand near the conclusion of Sunday's Brickyard 400.

“

These race cars are hard to pass on this track. It seemed like the guy that got out front had a big advantage and we needed to be out front.

”

-- GREG BIFFLE

With four fresh tires, Biffle may have had the fastest car on the track over the final 15 laps. But stuck behind eventual winner Jamie McMurray and second-place Kevin Harvick, "dirty air" did in any chance Biffle had of getting to the front.

While McMurray was running without turbulence, Biffle was struggling with the aerodynamic effects caused by the rear spoiler, used for the first time Sunday on NASCAR's current chassis design at Indianapolis.

"It's really unbelievable, the difference," Biffle said. "It's like you've got brand-new tires when you're out front and like you've got 20-lap tires when you're six car-lengths behind a guy. The thing just stops. It just slides all four tires.

"I was behind Kevin and just sliding the front and sliding the back right up against the fence and I just couldn't get the gas down. I just couldn't get enough of a run to get to him."

Jimmie Johnson wasn't a factor after handling problems put him well back in the field, but he also noticed how hard it was to pass cars all day.

"My car wasn't driving right, so it's tough to say, "Johnson said. "But I didn't see many people moving forward. You'd get one or two positions and that was it. I think it's more difficult to pass with the spoiler just because there's no air coming below the wing like we used to have. The spoiler just kicks the air higher and it makes a bigger hole behind the car."

How critical was track position? Of the six cars which opted for two tires on their final pit stops, none finished worse than 11th. Track position directly figured into the decision made by McMurray and crew chief Kevin Manion to take only two tires on their final pit stop, although McMurray was kicking himself for what he felt was a poor restart that allowed Harvick to edge back in front just as the final caution came out on Lap 147.

"When I got out in front, I honestly didn't think anybody would catch me," McMurray said. "[Harvick] hadn't been as good as us all day. I thought I'd be able to drive away from him. I got really tight. Kevin got up underneath me. I kind of let him go because I was going to try to cross over going into [Turn 1].

"As soon as I let off the gas, the caution came out. I was pretty frustrated."

But McMurray made amends by making sure his tires were up to pressure when the green came out with 10 laps to go.

"When Kevin gave me the outside, I thought that was my only chance," McMurray said. "On the restart we both spun the tires really, really bad. But when I got down to Turn 1, my car had a lot more grip than it did the run before. I don't know if the air pressure built up.

"I worked my tires in really, really hard under the yellow to get the pressure built up. Man, I just had way more grip that last run than I did the run before that."

Like McMurray, Harvick gambled on track position, which put him in position to grab the lead heading into the final restart.

"I just went into [Turn 1] and had to wait on the throttle a really long time because the car started chattering and Jamie just drove around me and it pushed the whole run there," Harvick said. "I felt like we had a top-five car, but didn't have a winning car and we had a chance to win there at the end but just came up a little short."

Tony Stewart also parlayed track position into a fifth-place finish.

"Those last two pit stops were very, very critical in getting us some track position," Stewart said. "We got some breaks there on one of the restarts that got us about three spots, so that got us the best track position we had all day. Those two tires weren't good enough to hold on at the end there, but we were a solid car."

Biffle couldn't really say if he thought he had anything for McMurray, even if he had been able to get by Harvick.

"I don't know because Jamie was about the same speed as Kevin, so I would have had the same issue with Jamie as I would with Kevin," Biffle said. "Four tires are only good for about five laps and then they start falling off and equalizing with the two-tire cars.

"You never know. I could have given him a try, but he was running a lot different line than Kevin was. Kevin was blocking the corner, entering low and really protecting that line. I saw Jamie really arcing it out, so I don't know if Jamie had to run there or he just was because nobody was pushing him. It's possible that we could have got up there and maybe got our nose inside of Jamie."

When the green flew for the final restart, Biffle was fifth and thought he might have a chance.

"My car was really, really fast all day," Biffle said. "I could just cut to the bottom and lay the throttle to it. I was closing on the guys 10 miles an hour faster than they were.

"I just drove by Tony on the short chute and just arced it out into three and to the bottom. The car was just so fast. It took me a few laps to get up to the back of [Harvick] and as you get further to the front the cars are running faster because they have less traffic. When you're back in traffic and the cars are slower, the four tires are way more effective -- at least it seemed like for me."

But in doing so, Biffle used up any advantage he might have had with fresher tires.

"These race cars are hard to pass on this track," Biffle said. "It seemed like the guy that got out front had a big advantage and we needed to be out front. We had a good car. I was way faster than Harvick, but just couldn't get by him."