A double-digit decline in ratings for NASCAR on Fox has officials researching why the audience is shrinking and what, if anything, can be done to reverse the trend.

Through the season's first 10 races, Nielsen ratings on Fox are down 11.5 per cent and viewership is down 10.8 per cent from 2008 numbers, which don't include a 2008 rainout. Ratings for each of the past seven Sprint Cup races going into last week's event at Darlington were down by double digits.

Fox's average rating for the season was a 5.4 with 8.9 million viewers before Saturday's race at Darlington, compared with averages of 6.1 and 10 million for 2008. The overnight rating for Saturday's Southern 500 was 16.3 percent lower than last year's race.

“As you look at the current snapshot, it's been a challenging year,” said Paul Brooks, president of NASCAR Media Group. “That being said, we're still the number one sport on television six of the last nine weeks. Our position in the sports and entertainment landscape is strong.

“The biggest impact is with our TV partners and their commercial sales. We're mindful of that. The flip side is that we hear great things, that it's not a NASCAR issue. It's a broader economy and advertising issue.”

Marketers in the sport have expressed some concern, not just over the drop, but how steeply the ratings have dropped. But for many sponsors such as UPS, NASCAR's official express delivery company, advertising is just one component of a multipronged program.

UPS advertises about as much as anyone in NASCAR, especially this year as it introduces a new driver, David Ragan, with five new spots.

“Is it a concern? Yeah,” said Ron Rogowski, UPS's sponsorship director. “You don't want to see something you're heavily invested in fall off, but you have to be careful and keep it in perspective. It's just one part of our program.

“Where it becomes more relevant is when you try to substantiate your investment.”

There's also the Dale Earnhardt Jr. factor. Earnhardt, the sport's greatest selling force and biggest star, has yet to hit his stride at Hendrick Motorsports. With Earnhardt standing 18th in points and owning one top-five finish this season, he has been unable to provide a Tiger Woods-like surge for NASCAR through his performance.