After 15 of 36 races, NASCAR’s premier Sprint Cup series takes a rare break this weekend. The second half of NASCAR’s marathon season kicks off the following weekend on Northern California’s Sonoma road course with 21 races to come in relentless order over the next 22 weekends through the end of November.

Thus far, defending champion Kevin Harvick has more often than not been the man to beat. Harvick won last year’s championship in his first year with Tony Stewart’s Chevrolet team and he’s been equally strong this year leading the points most of the way. Thus far Harvick has a record of two wins, eight second places and three more top 10 finishes. He’s also led all but one race for a total of 1225 laps, twice as many as anyone else and three times his closest challengers Jimmie Johnson and Martin Truex.

Harvick has firmly established himself as Stewart-Haas Racing’s team leader, although Kurt Busch has also been very competitive in many races. After missing the Daytona 500 and two other races because of a legal dispute with his former girlfriend Busch has rebounded well, taking three poles and winning at Richmond in April and Michigan last weekend. Despite missing three early races Busch is 12th in points and has led a total of 689 laps.

Daytona top 10

1 Joey Logano Penske Ford
2 Kevin Harvick Stewart-Haas Chevy
3 Dale Earnhardt Jr Hendrick Chevy
4 Denny Hamlin Gibbs Toyota
5 Jimmie Johnson Hendrick Chevy
6 Casey Mears Germain Chevy
7 Clint Bowyer Waltrip Toyota
8 Martin Truex Jr Furniture Row Chevy
9 Kasey Kahne Hendrick Chevy
10 Greg Biffle Roush Fenway Ford

Last year was a tough one for team owner Stewart as he suffered from leg injuries and also the mental strain of his role in the death of Kevin Ward Jr in a sprint car race in upstate New York. But Stewart has endured a poor season in his return to action and is a lowly 26th in points with only one top 10 finish. Danica Patrick drives Stewart-Haas’s fourth Chevrolet and is having a typically mediocre season. She’s 19th in points, scraping into the top 10 in two races, which is at least better than her boss…

Harvick’s biggest challengers at this stage of the season are six-time champion Jimmie Johnson with Rick Hendrick’s Chevy team and Martin Truex Jr, who’s surprised everyone with his consistently competitive runs in Barney Visser’s Chevy team. Truex scored his first win for Visser’s team at Pocono a few weeks ago.

Johnson has won a series high four races to date and Hendrick team-mates Jeff Gordon, Dale Earnhardt Jr and Kasey Kahne are in the top 10 in points as well. Johnson took his 74th win at Dover two weeks ago and is closing in on seven-time champion Dale Earnhardt (Sr)’s tally of 76 wins. Johnson is as strong as ever and many pundits believe this year’s championship will come down to a battle between Johnson and Harvick.

At this point Truex is the spoiler. In his second year with Visser’s single-car Furniture Row team Truex has been competitive everywhere and seems to be getting stronger as the season wears on. Two years ago Truex lost his job with Michael Waltrip’s team after a race-fixing scandal involving team-mates Clint Bowyer and Brian Vickers drove Truex’s sponsor NAPA away from Waltrip.

But Truex has bounced back in style with Visser’s small team. Right now he’s in the middle of negotiating a new contract with Visser, who may switch from Chevrolet to Toyota next year. Visser is also looking for more sponsorship to help cement a long-term deal with Truex.

Other possible championship contenders include Joey Logano and 2012 champion Brad Keselowski driving Fords for Roger Penske. Logano won the season-opening Daytona 500 and Keselowski won at the California Speedway in March. Logano and Keselowski are fourth and sixth in points right now, bracketing Earnhardt.

It’s hard to imagine anyone else putting up a championship challenge. Each of Matt Kenseth, Denny Hamlin and Carl Edwards have won one race in Joe Gibbs’ Toyotas but overall they’ve been disappointing. Team-mate Kyle Busch missed eleven races after breaking his leg in an accident at Daytona in February. He’s back and is as quick as ever, but an unlikely championship threat.

Of course, NASCAR has its problems with declining crowds and TV ratings. Crowds continue to decline at many traditional races like Bristol, Charlotte and Dover, but many newer tracks in the west and south west – such as Phoenix, Las Vegas and the California Speedway – are doing well. TV ratings started well this year but tailed off a little in recent months and for the first time in a decade the Indy 500 outdrew Charlotte’s 600-mile race run later on Sunday night.

Not that this should be read as a turnaround for IndyCar. The TV audience for your average IndyCar race is one-tenth the size of NASCAR’s audience but there’s no solace for NASCAR in the fact that it regularly draws a smaller audience than CART pulled 20 years ago.

Yet NASCAR remains the big dog of modern American racing with a much bigger, stronger schedule and much more media coverage and an infinitely bigger fan base than either IndyCar or United SportsCar.

More than 40 tractor-trailer rigs, or ‘haulers’, representing at least 25 teams show up for most Sprint Cup races. Many NASCAR teams are multi-car operations, running two, three or four cars. So far this year 30 drivers have started all 15 races run while no less than 63 drivers have started at least one.

Defending champion Harvick leads everyone at mid-season with almost $5 million in prize money while so far this year no fewer than 38 drivers have earned $1 million or more. This represents a very different and much more equitable pay-out down through the field than Formula 1 and is an essential component in NASCAR’s overall good health.