Jimmie Johnson, Nascar's Sprint Cup Series champion every year since 2006, isn't particularly charismatic. But he's great at what he does. He's also appealing to many fans because he seems to be just like them--the guy next door who just happens to double as the best driver on the Nascar circuit. That's among the reasons why Johnson rates as America's most influential athlete this year.

After a prolonged slump, "Nascar has had a bit of resurgence, people are becoming more aware of the drivers this year," says Gerry Philpott, CEO of Encino, Calf.-based E-Poll Market Research, which co-conducted the poll of influential athletes our list is based on. While the sport is still lagging behind the glory days of the early 2000s, television ratings are up 6% this year, according to Nascar Chief Marketing Officer Steve Phelps, who credits competitive early races this season with drawing interest. "It helps drive story lines," says Phelps. The first nine races of the 2011 season have produced seven different winners. Jeff Gordon, a longtime fan favorite, got a nice boost from making it into the winner’s circle in Phoenix in February, his first victory in two years.

Combined with the retirement of Lance Armstrong, the diminished reputation of Tiger Woods, and the fading of interest in 2010 winter Olympians like Apolo Anton Ohno and Shaun White, the mini-rally has launched three Nascar drivers into the ranks of the most influential athletes. Dale Earnhardt Jr., who certainly is charismatic, and Gordon, a steady and likeable presence since the early 1990s, join Johnson in the top 10 in third and eighth place, respectively.

E-Poll and Nielsen Media Research surveyed over 1,000 adults as to the athletes they considered influential, while also assessing their likeability and awareness levels. Only those known to at least 20% of the respondents were considered. (That eliminated boxer Manny Pacquiao, who scores the highest influence numbers of anyone but who's familiar to only 12% of the population. What does it say about boxing that its most exciting champion toils in near anonymity?)

Talent is just part of what makes an athlete "influential" to the public. Endorsements and media attention, along with off-the-field image all factor in. In short, has the player raised interest in the sport he plays?

The polling shows certain qualities help a player win influence with the public: being intensely competitive without ostentation, and valuing winning above calling attention to yourself. And (mostly) avoiding big controversies off the field.

The overall influence ratings of big-time athletes are down in the U.S. from a year ago, with the average athlete rated as "influential" by 11% of respondents, off three percentage points. "Our hunch is that strikes [or lockouts] along with other situations like Tiger Woods have affected things," says Philpott. "The rose is off the bloom a bit." The makeup of the top 10 has turned over quite a bit, too. Gone from last year: Lance Armstrong (our list is for active athletes only), White (now that we're a year past the 2010 Winter Games), Ohno (ditto), and NBA stars Kevin Garnett, Dwayne Wade and Kobe Bryant (probably just random, though Wade's stature decreased a tad with LeBron James joining his team, and Garnett is another year older). Armstrong, who was accused a year ago by former teammate Floyd Landis of doping, would have likely dropped off the list anyway, notes Philpott, even amid his vigorous denials. Short of proving your innocence, the controversy will take a toll, guilty or not.

Still on the list but dropping from last year are LeBron (No. 2 to No. 9), whose 2010 "Decision" didn't please many fans, and Denver Broncos quarterback Tim Tebow (No. 3 to No. 10), who went from college star and first round NFL draft pick to mostly benchwarmer as a rookie. Nonetheless Tebow still holds the interest of NFL fans who wonder if his unconventional game will succeed in the pro ranks. One other thing about Tebow: his reputation for clean living and willingness to show his Christian faith publicly mostly serve to make him popular, though it's a bit polarizing. The 13% of respondents who say they "dislike" Tebow or "dislike him a lot" is the most of anyone but James (15%), even as many more claim to like him.

Moving onto the list this year are New England Patriots quarterback Tom Brady, ranking second after capturing the NFL MVP Award; Steelers safety Troy Polamalu, whose star has been steadily climbing in recent years; and swimmer Michael Phelps, who has quietly put that 2009 bong picture flap to rest while benefiting from the exposure of the approaching 2012 Olympics.

Notably missing from the list: Major League Baseball players. Chalk it up to the tribal nature of fans of that sport--big-name players like Joe Mauer, Derek Jeter and Albert Pujols score far higher in their local markets than they do nationally, says Philpott.

Full List: The Most Influential Athletes