But lately, that quest has become more imperative, for after two decades of supercharged growth, huge attendance, and stunningly lucrative corporate sponsorships and TV deals, the oval-track racing circuit has hit a rough patch. Race-day seats are going unsold, and TV ratings are flat or falling—a development that factored into NBC’s decision to pull out at the end of the 2006 season after having broadcast races since 2001. (The contract has since been picked up by ABC and ESPN.)

The job of reversing these trends has fallen to Brian France, Big Bill’s 45-year-old grandson and the son of Bill France Jr. Though he officially took over as Nascar’s C.E.O. only four years ago, France is known as a business progressive and is widely credited for some of Nascar’s best growth years. For example, France—sometimes over the objections of Nascar’s fans, drivers, and owners—moved races out of various Southern boondocks and into big media markets like Chicago, Los Angeles, and Las Vegas, all in the name of increasing Nascar’s visibility. For a publicity gimmick in November, he had Nascar racers zoom down Broadway through New York’s Times Square.

Now, having wrung the easy growth out of moves to urbanize the circuit, France is convinced that Nascar can continue to grow only if it broadens its minority fan base, which sits stalled at about 18 percent of its audience and is divided equally between blacks and Hispanics. In his state-of-the-sport address given at the beginning of the 2007 racing season, France spoke openly about the need for change. “I remain not only committed but convinced that if we don’t get diversity right, this sport will not achieve what it needs from a popularity standpoint, won’t get the best drivers, won’t get the best talent on the management side, won’t get the fan base that we deserve,” he told reporters. He later admitted there’s a tricky part to this: How does Nascar attract a more diverse audience without alienating those good-old-boy fans? Or put another way: Could doing the right thing turn out all wrong for Nascar’s growth plans?

Marc Davis may one day break out as a top-ranked, lucratively sponsored black driver, but the story of 46-year-old Bill Lester is probably more illustrative of the challenges black drivers have faced during the past decade. For several years, Lester drove in the third-tier Craftsman Truck Series (Nascar’s tiers aren’t all that different from Major League Baseball’s farm club system) and was the only minority driver competing full-time in Nascar. When he made his Nextel Cup debut at Atlanta Motor Speedway in 2006, he was the first black driver to reach Nascar’s highest rung in 20 years. As the 2007 season got under way, team owner Billy Ballew announced plans to enter Lester in at least four Nextel Cup races. By the end of the season, however, Lester not only hadn’t competed in a race, but his career at even the Craftsman level was essentially over. Though Nascar boasts 106 Fortune 500 companies as sponsors, Lester was unable to secure a financial backer, Fortune 500 or otherwise, and ended up sidelined in mid-August with 10 races to go.

One African American with a bird’s-eye view of Nascar and extensive knowledge of its diversity efforts is former N.B.A. star Brad Daugherty, who once owned a Nascar Craftsman Truck Series and Busch Series team and now provides commentary on Nascar races for ESPN. Daugherty, who got hooked on the races while growing up in North Carolina, says the sport’s overwhelmingly white, Southern fan base makes many corporate sponsors reluctant to put their money behind a black driver for fear of a fan backlash against their products. “I had trouble with the corporate people, because they wanted to dictate who was on my race team and who I put in that truck,” Daugherty says of his efforts to sign up a black driver. “If you’re going to put an African American or a face of color in your truck, your corporate sponsors have to agree,” he says. “I’ve sat in meetings with Fortune 500 companies that are interested in helping me put together a program, but at the end of the day, all they want to know is ‘How does Nascar feel about it?’ ”