The NASCAR Sprint Cup Series drivers were busy at work on Friday at Indianapolis Motor Speedway, with three 85-minute practice sessions in preparation for this weekend's Crown Royal 400 event.

CLICK: Full Friday practice session times from the Indianapolis Motor Speedway.

The first session was laid on to allow teams and drivers to get used to a new aerodynamic rules package, designed to make the cars less smooth through the air to encourage more exciting side-by-side racing. Denny Hamlin proved the quickest learner with the new set-up and finished fastest with a lap of 49.394s (182.208mph) on the two-and-a-half mile speedway in the morning.

Related Articles

That proved to be the fastest time that anyone was able to run all day. However, it was slower than the 186.285mph that his Joe Gibbs Racing team mate Matt Kenseth had achieved in the same session 12 months ago, let alone Kevin Harvick's 2014 pole speed which had clocked in at 188.470mph. On this evidence, today's times appear to be at least 4mph slower as a result of the new aero specification, which includes a raised rear spoiler capped by a new wicker bill on top. Drivers complained on Friday that the change has affected rear view visibility despite the new components being made of a clear plastic material.

"That wicker, you can't see anything behind you with that wicker on there," Dale Earnhardt Jr. said. "I can't see anything behind me as far as cars coming. I can't tell what's going on back there. You're going to have to tell me so I don't stop in front of somebody, or slow down too quickly in front of somebody or pull out in front of somebody."

Hamlin's best lap was 0.112s faster than that of Hendrick Motorsports' Jimmie Johnson, who suffered a fuel-pressure issue midway through the morning session that brought the #48 to a stop out on track. "The car shut off instantly," Johnson explained later. "The fuel pressure gauge was spinning around and went red. So I think that might be the first place to look."

Johnson got a nudge back to the pit road entry from Stewart-Haas Racing owner-driver Tony Stewart, whose team mate Harvick ended the session third fastest just ahead of Johnson's colleague Jeff Gordon who is making his final appearance at IMS before he retires from competition at the end of the season. Stewart himself was fifth fastest just in front of JGR's Matt Kenseth.

Paul Menard scrapped the turn 1 wall 30 minutes and just three laps into the session, causing some minor damage to the Richard Childress Racing #27 that the crew was quickly able to repair meaning Menard avoided having to break out the backup car. Despite the mishap, Menard was still fast enough to be credited in 12th place by the end of the session.

In the second practice which got underway at noon, the third Hendrick car of Dale Earnhardt Jr. quickly went to the top of the timesheets with a lap of 49.596s (181.466mph) which was five thousandths of a second faster than Penske's Brad Keselowski. The remaining member of the four-car Hendrick line-up, Kasey Kahne, clocked in with the third fastest time ahead of Chip Ganassi Racing's Kyle Larson.

"Real good," commented Earnhardt afterwards. "A little snug on the first half of the corner, a little edgy on the back half of the corner. Turn 1 is really good," he said, adding: "I need to be smoother off of the throttle, it makes it tighter."

Hamlin ended the second practice with the 12th fastest time after a bizarre incident early in the session when the hood on the #11 suddenly came loose having not been properly secured. It snapped up and damaged the windshield and front of the car, but the JGR crew was able to repair the damage and get Hamlin back out on track without recourse to the backup vehicle.

"It blew the roof apart a lot and did some damage inside the car," Hamlin explained. "It's just a lot of force there that tears up a lot of stuff any time the hood comes up." Hamlin's mishap triggered the first of two red flags for debris, while the second was for a weight that came off Timmy Hill's #98 Ford.

The final practice saw SHR took a firm grip of the proceedings, with Kurt Busch leaving it late to surge to the top with a best time of 49.454s (181.987mph) to narrowly pip his team mate Harvick by 0.061s. Larson continued to feature strongly in third place ahead of Johnson, with Furniture Row Racing's Martin Truex Jr. in fifth place having improved in each session and finished each of the day's session in the top ten.

Premium Motorsports had to break out the backup #98 car for Hill early in the final practice after he went nose-first into the turn 4 wall just eight minutes into the session. Hill was unable to set a time for the session and was classified last of the 46 drivers in action on Friday.

There will be no more practice sessions before Sunday's race. Qualifying for the Crown Royal 400 will take place on Saturday afternoon at 12.10pm local time (6.10pm BST) and will take the form of two rounds of single car time trials rather than the group format used at shorter circuits.

See full Friday practice session times from the Indianapolis Motor Speedway.