•The races, typically at three-plus hours, were too long for a nation with a seemingly shorter attention span and more technology choices, such as following races on the Internet.
•Jimmie Johnson, the Californian who has captured the Cup title the last five consecutive years, won too much.
•Dale Earnhardt Jr., the most popular driver, seldom won at all.
•NASCAR's late-season playoff, the "Chase for the Cup," lacked sufficient drama because its points system prompted drivers to focus more on consistent finishes than winning.
•Johnson and other drivers were bland personalities, and too many tracks looked alike. And there weren't the headline-grabbing driver rivalries to draw casual fans.
But talk to people involved in NASCAR and most keep pointing back to one decisive culprit: The new race car that NASCAR mandated starting in 2007 in the Cup series turned off many drivers and fans.
NASCAR dubbed it the "Car of Tomorrow," or COT. Designed mostly for enhanced driver safety following the 2001 death of seven-time champion Dale Earnhardt Sr., the car was unlike anything seen before.
It was boxy, had a rear wing and, even in a sport where cars had little resemblance to "stock" cars on the street, this one had almost no resemblance. Worse, the COT's new chassis and steering system were temperamental to drive and hindered the passing that NASCAR fans crave.
After winning the first COT race, brash driver Kyle Busch told a national TV audience what many others in NASCAR garages were whispering. "I can't stand to drive" the new car, Busch said as he stood in Victory Lane. "They suck."
Suddenly, NASCAR had a big problem.
"If you look at something that hurt [the sport], that hurt. That car alienated a lot of fans," said driver and team owner Michael Waltrip.
NASCAR also "thought the competition [on the track] would be good enough that it wouldn't matter" what the car looked like, said Howard Comstock, Dodge's engineering program manager for NASCAR. "It did matter, it mattered a lot to the fans."
The car was part of "a disconnect" that opened between NASCAR and its fan base, agreed Julie Sobieski, a vice president at ESPN, which with its broadcast sister ABC splits the Cup series' telecasts with Fox and TNT.
In retrospect, NASCAR President Mike Helton said, "If we had that opportunity to go back . . . we would probably introduce [the car] differently," although he didn't offer specifics.
Regardless of what NASCAR thought about the car, "the perception is that it was" a big factor in NASCAR's popularity decline even if it kept drivers safer, he said.
Some also cite last year's decision by Walt Disney Co. to shift most of its NASCAR telecasts from over-the-air ABC to cable's ESPN as a contributor to the ratings drop.
John Saunders, president of International Speedway Corp., which operates 13 NASCAR tracks, said the switch lopped 15 million homes from potential viewership "right out of the gate." NASCAR and ESPN expect the change to eventually pay off, especially among the 18-to-34 age group that they and advertisers covet.
And ESPN wasn't solely the problem; ratings on Fox and TNT fell too.
Regardless, Helton rejected the notion that NASCAR had reached a peak that can never again be matched.
Even in the heady days when Ricky Bobby raced for laughs on movie screens nationwide, Helton said, "we never were happy with where we were."
Next: How NASCAR hopes its popularity can gain speed again.