With the continuing development of NASCAR's new race car, the Gen-6, track activities for Sprint Cup Series teams at Las Vegas Motor Speedway this week will begin sooner than normal.

Teams will be testing the car at Las Vegas throughout the day on Thursday. The test should provide drivers and crew chiefs with more valuable information on how the car will perform on intermediate racetracks, which are tracks that are one mile or more but less than two miles in length.

Las Vegas is the first of 11 Sprint Cup races that are contested on 1.5-mile tracks this season. Teams tested at Charlotte Motor Speedway, which is also a mile and a half, twice during the offseason.

"Without a doubt, the 1.5, two-mile tracks can make your entire season," said Steve Letarte, who is the crew chief for the No. 88 Hendrick Motorsports Chevrolet, driven by Dale Earnhardt Jr. "As a crew chief, you are trying to figure out what area you should be working in."

Last year, Earnhardt finished no worse than 10th in the races that he competed in at 1.5-mile tracks. He sat out the fall events at Charlotte and Kansas due to a concussion. Earnhardt won the June race at Michigan, which is a two-mile oval.

In addition to Thursday's test, teams will practice on Friday and Saturday, in preparation for Sunday's 400-mile race at Las Vegas.

"With it being an intermediate track and a place that's really fast, the aero part becomes the biggest thing that you fight, and I think everybody in the garage needs to learn a little bit (more) about this new car and where the splitter needs to be compared to the racetrack," said crew chief Rodney Childers, who oversees the No. 55 Michael Waltrip Racing Toyota that Mark Martin put on pole last weekend at Phoenix.

Since the season-opening race, the Daytona 500, was contested on a restrictor- plate track, the Gen-6 got its first true test in competition at Phoenix, which is a one-mile oval.

After extensive offseason testing and now two races completed this year, drivers and teams are finding out the Gen-6 cars -- Chevrolet SS, Ford Fusion and Toyota Camry -- are faster and have more downforce and better grip than the most recent cars, which were used from 2007-12.

But drivers have noticed some other things about this car. Passing has been difficult, and there hasn't been much side-by-side racing.

"I think (this) week in Vegas we have a track that has multiple lanes, and we'll see some great side-by-side racing," Hendrick Motorsports driver and five-time Sprint Cup champion Jimmie Johnson said. "The garage area and the teams and owners and the competition side of NASCAR have worked so hard to make these cars equal, and we keep changing and jumping through hoops, new chassis, new bodies, new this, new that. The cars are equal, and when they're equal, you're going to have a situation like this. What we need now is the racetracks to consider the asphalt they're putting down and even reconfigure the lanes so that we have somewhere to race."

Johnson, who holds an eight-point lead after winning the Daytona 500 and finishing second at Phoenix, continues to have a favorable opinion of the car.

"I think we have a great product," he said. "It's going to continue to get better. One of the things that we've all recognized over the years is the faster we go the narrower track gets the harder it is to pass. Speeds will be up, especially when we get to the mile and a halfs, so with all that being said, I think we need to leave the cars alone for a good 10, 20 years. Let the teams be. There's a lot of work that can be done to help create better racing and keep the fans in the grandstands."

Johnson has the most wins at Las Vegas with four. He won three consecutive races here from 2005-07. His other victory at this track came in 2010.

Forty-four teams are on the preliminary entry list for the Kobalt Tools 400.

Series: NASCAR Sprint Cup. Date: Sunday, March 10. Race: Kobalt Tools 400. Site: Las Vegas Motor Speedway. Track: 1.5-mile oval. Start time: 3 p.m. ET. Laps: 267. Miles: 400. 2012 Winner: Tony Stewart. Television: FOX. Radio: Performance Racing Network (PRN)/SIRIUS NASCAR Radio.