Entry list

The entry list for the Kobalt 400 was released on Monday, March 2, 2015, at 9:00 a.m. Eastern time. Forty-eight drivers are entered for the race. All 48, except Ryan Blaney and the No. 21 Wood Brothers Racing Ford and Ty Dillon, were entered to race the previous week in Atlanta. Dillon drove the No. 33 Hillman-Circle Sport LLC Chevrolet. No driver was on the initial entry list to drive the No. 34 Front Row Motorsports Ford in place of David Ragan who drove in place of the injured Kyle Busch. On Wednesday, March 4, Brett Moffitt, coming off an 8th-place finish at Atlanta, was named to drive the No. 34 car.^[14] Moffitt stated that he was "excited about the opportunity to run some races for Front Row",^[14] and that he was "grateful to Bob Jenkins and his team for giving me the chance to do that". Brian Vickers, the driver who Moffitt was driving in place of – at Michael Waltrip Racing – was in the No. 55 Toyota, having missed the first two races while recovering from corrective heart surgery.^[15]

Start

The race was scheduled to start at 3:46 p.m. Eastern time, but started a couple of minutes later when Kasey Kahne led the field to the green flag. He was immediately passed by Joey Logano who took the lead on the second lap. Jeff Gordon, who dropped to the rear of the field for switching to a backup car, moved up to 24th in the first 20 laps. He made it to 21st in the running order when the first caution of the race flew on lap 26. This was a scheduled competition caution, normally done when there has been overnight showers, to allow teams to check tire wear. As Logano was trying to exit pit road, Jeff Gordon, whose stall was right in front of his, blocked his exit momentarily and Dale Earnhardt Jr. exited pit road as the leader. Alex Bowman stayed out to lead a lap before pitting and giving the lead to Earnhardt. Unfortunately for Bowman, his engine started blowing up and he was forced to take his car to the garage.^[24]

The race restarted on lap 31 and it did not take long for Logano to find his way back to the lead. Jimmie Johnson reeled in Logano and took the lead on lap 44. Earnhardt Jr. had pulled up to him by lap 63, but had trouble getting around lapped traffic and Johnson pulled away. A number of cars began pitting on lap 75. Johnson gave up the lead on lap 77 to pit and handed the lead to Carl Edwards. He pitted on lap 79 and handed the lead to Matt Kenseth. He pitted the next lap and the lead cycled back to Johnson. Brendan Gaughan and Brian Scott were forced to serve a drive-through penalty for speeding on pit road.^[24]

Green flag stops

Debris in turn 1 brought out the second caution on lap 82. This was a saving grace for Brad Keselowski who was reporting a vibration. Aric Almirola was forced to drop to the end of the longest line for speeding on pit road, as did Tony Stewart, as a tire rolled out of his pit box. The race restarted on lap 87. Four laps later, Kevin Harvick powered his way around Johnson, who made an unscheduled stop for a loose wheel, to take the lead. He rejoined the race 33rd one lap down. The next set of green flag stops began on lap 129 when Martin Truex Jr. gave up tenth to pit. Harvick gave up the lead on lap 132 to hit pit road and Keselowski took the top spot. He held the lead for two laps before pitting on lap 134. This allowed his teammate Joey Logano to retake the lead. Keselowski was forced to serve a drive-through penalty for an uncontrolled tire rolling out onto the tri-oval grass area, which brought out the third caution of the race on lap 139.^[24]

Trouble for Johnson

The race restarted on lap 178. The fifth caution flew with 82 laps to go when Jimmie Johnson blew another right-front tire and again hit the wall again in turn 4.^[25] Upon exiting his car, Johnson explained that on the first puncture, his team believed that "the bead blew on it", while on the second puncture, the tire "went soft going into Turn 3 and I hit the wall, unfortunately".^[25] Joey Logano was again sent to the back of the line, for speeding on pit road. The race restarted with 75 laps to go. Carl Edwards pushed Kasey Kahne into the wall exiting turn 4. Kahne, in retaliation, turned down on Edwards in turn 1 and sent him spinning, bringing out the sixth caution of the race with 74 to go. During the period, Aric Almirola was again caught speeding on pit road.^[24]

Final stops

The race restarted with 69 laps to go and Dale Earnhardt Jr. took back the lead. He would lose it two laps later to Harvick. He made his final stop with 37 laps to go and handed the lead to Ryan Newman. He went until 25 laps to go before pitting and handing the lead to Brad Keselowski. He pitted with 17 laps to go and Kevin Harvick cycled back to the lead and coasted to his 29th career victory.^[26]

Driver comments

Harvick felt that it was "so cool to win here in Las Vegas and start this West Coast swing off this way is pretty awesome" and that he was "glad the race is over at that particular point for our own good".^[26]

Post-race penalties

The No. 51 team was penalized for a rules infraction discovered during post-race inspection March 8 at Las Vegas Motor Speedway. This infraction is a P3 level penalty and violates the following Sections in the 2015 NASCAR rule book:

• 12.1: Actions detrimental to stock car racing;
• 20.3.5: Added ballast containers:
  • a. Any and all ballast added to the vehicle must be bolted inside an added ballast container, inside the main frame rails, and/or inside the front sway bar.
  • b. Added ballast must be secured in a manner that will prevent movement of the ballast during an event.
• 20.17.2.2: Overall vehicle weight after competition:
  • b. After a vehicle has raced, only water in the radiator, oil in the engine reservoir tank, and fuel in the fuel cell may be added. Wheels and tires may not be changed, unless otherwise authorized by NASCAR Officials.
  • c. After a vehicle has raced, the minimum overall vehicle weight of all vehicles must be within 0.5% of the minimum overall vehicle weight required at the start of the race.

Ballast was observed falling off the No. 51 car during the race and the No. 51 car did not meet post-race minimum weight requirements. As a result of the violation, crew chief Steve Addington was fined $25,000.^[27]

The No. 2 team was penalized for a rules infraction committed when it was discovered that the right and left rear quarter panel wheel openings were modified after qualifying inspection on March 6. This infraction is a P2 level penalty and violates the following Sections in the 2015 NASCAR rule book:

• 12.1: Actions detrimental to stock car racing;
• 20.4.b: Body – All approved OEM-manufactured body components must be used as supplied except as required to stiffen, or to attach to other vehicle components. Tolerances from CAD surfaces and template tolerances are provided to allow for manufacturing, fabrication, and installation variability;
• 20.4.2: Surface Conformance – Coordinate measuring machines, scanning equipment, and templates, among other tools, will be used to inspect body surfaces for conformance to the approved OEM and NASCAR CAD files.

As a result of this violation, crew chief Paul Wolfe was placed on NASCAR probation through December 31.^[27]

Race awards

• Coors Light Pole Award: Jeff Gordon (27.738, 194.679 mph (313.305 km/h))
• 3M Lap Leader: Kevin Harvick (142 laps)
• American Ethanol Green Flag Restart Award: Kevin Harvick (30.537, 176.833 mph (284.585 km/h))
• Duralast Brakes "Brake in The Race" Award: Jeff Gordon
• Freescale "Wide Open": Kevin Harvick
• Ingersoll Rand Power Move: Austin Dillon, 8 positions
• MAHLE Clevite Engine Builder of the Race: Hendrick Engines, #4
• Mobil 1 Driver of the Race: Kevin Harvick (141.5 driver rating)
• Moog Steering and Suspension Problem Solver of The Race: Kevin Harvick (crew chief Rodney Childers, 0.306 seconds)
• NASCAR Sprint Cup Leader Bonus: Kevin Harvick: $30,000
• Sherwin-Williams Fastest Lap: Kyle Larson (Lap 2, 29.285, 184.397 mph (296.758 km/h))
• Sunoco Rookie of The Race: Jeb Burton