...Tivo-Proof: The number of corporations willing to pay big money to sponsor stock-car racing teams appears to be dwindling, thanks in part to troubled business sectors. In March, for example, besieged mortgage lender Ameriquest withdrew its sponsorship of Roush Fenway's No. 16 car, driven by Greg Biffle, two years before the contract was up.

While the powerful Roush Fenway team will no doubt find a sponsor for Biffle's ride, corporate boosters appear to be holding the line on their investments. This is understandable. Primary sponsorships are getting pricey, now between $15 million and $20 million. Even lower-profile sponsors, so-called major associates, pay anywhere from $2 million to $4 million to put a decal on the rear deck lid of a stock car.

Until recently, backing a Nascar team was one of the best buys in marketing. A corporate logo emblazoned on the hood and trunk of a race car is perfect product placement -- "Tivo-proof" is how one racing executive puts it. In fact, sports-marketing specialist Joyce Julius & Associates reckons all sponsors involved in Nascar's top series, the Nextel Cup, received $5.2 billion in TV exposure last year. That's up 353 percent from 1997.

But with Nascar's television numbers dipping -- down 12 percent from 2005 -- sponsors are getting less mileage out of their investments. (TV ratings for other pro sports are falling, too.) Not surprisingly, sponsors are becoming more selective. "There's a lot of competition for sponsors right now," says Larry DeGaris, president of sports-marketing firm Sponsorship Research & Strategy. "Teams are going to be selling against each other."

That will be hard on smaller racing outfits, particularly one-car teams. Once the dominant force in the sport, these small shops are finding it increasingly difficult to attract corporate funding. Of the nearly 50 drivers currently on the Nextel Cup series drivers list, only 7 are employed by single-car operators...