ylvester Stallone is a driven man. In Toronto in July shooting his "Rocky on wheels" during the three-day lakefront Molson Indy, he is once again champion of the underdog, this time in the car racing world.   In Driven (formerly called Champs) Stallone is a retired driver brought back into the action to help a rookie sensation get on track. "No one wanted to make it," recalls Stallone, comparing it to his Oscar-nominated Rocky. "It was what I went through 25 years ago."?   Stallone, who also wrote the script, said he was intrigued by the subject matter. He said he liked how "the life and death" professional existence of the drivers affects their stressful lives.   The film is based on the FedEx Championship Series, although originally he had planned to use the Formula One circuit as a backdrop for the film. He abandoned that notion when he was unable to obtain full cooperation. Driven, directed by Renny Harlin, is now set in the world of CART (Championship Auto Racing Teams) racing. Many of the CART racers are expected to have cameos or supporting roles. Says Stallone, "It's extremely important to me that we create a film that accurately depicts the emotion, excitement, speed, technology and glamor that is car racing. He even had his own pseudo racing team semi-trailer in the Indy paddock.   A car buff from way back, Stallone's own car of choice while in shooting in Toronto and Montreal was a Hummer, leaving plenty of room for his wife, ex-supermodel Jennifer Flavin and their two kids.   Although Stallone became one of Hollywood's most highly paid actors after the success of the Oscar-winning Rocky, usually playing monosyllabic, antisociety underdog heroes, he has attempted to extend his range into film comedies and drama (particularly in 1997's Copland, where he worked for a mere $60,000) in order to let audiences see a different side of him. But his real box office success continues in action films.   "I don't know why action movies have become the movie business' equivalent of The Hunchback of Notre Dame," Stallone once said to Interview magazine.   "Just as Quasimodo was the ugly duckling in literature, action films have become the sore spot for critics. When we make an action movie now, we're considered moneymaking machines with no esoteric worth, and that's not true at all. There's a lot of artistry that goes into what we do. I tend to think of action movies as exuberant morality plays in which good triumphs over evil."   Although an affable guy, in 1997, he was trailing in neighbor of the year balloting. He first un-endeared himself to Miami residents by persuading the city to build an iron gate near his mansion, sealing off a popular walkway. Then he added to his lack of local popularity by setting up buoys on the waters of Biscayne Bay near his estate, issuing a succinct "keep out" warning on the floating turf. He was later slammed by residents of the area for mulling an offer to sell his mansion to a hotel developer. The 24,000 square-foot village in Miami and its three guest houses eventually sold after two years on the market for $20-24 million.   Stallone didn't start his life destined for success. With his two trademark features, drooping eyes and slurred speech, he had a difficult childhood in New York's Hell's Kitchen growing up. But his childhood problems didn't hurt him later in life.   "I'm not handsome in the classical sense. The eyes droop, the mouth is crooked, the teeth aren't straight, the voice sounds like a Mafioso pallbearer, but somehow it all works." - Rise Levy