You can divide the automotive universe into two categories: those who paid too much for a new car and those who think they did. Such is the maddening process of visiting dealers, deciphering their "real" cost, and negotiating the labyrinth of fees. Revolutionizing the MO of car buying is the crusade of Scott Painter, the 43-year-old founder and CEO of TrueCar.com. Starting Jan. 1, his website will become Yahoo's exclusive partner for car shoppers.