Electronic Arts' free-to-play PC racing MMO Need For Speed World has passed 5 million registered users, the company announced today, less than a year after its July 2010 launch. The title reached the 1 million player milestone last September and surpassed 3 million players in December. EA is using the game to show off virtual versions of real world cars from Audi, including and exclusive version of the A1 Clubsport Quattro, which was unveiled today at a car show in Austria. Need for Speed World players will be able to try out the car for free through June 4. Seventeen other current Audi production models are among the dozens available for use in the game, which can all be visually customized to player specifications. Need for Speed World is part of EA's Play4Free line, which includes free-to-play online titles in the Battlefield, Dragon Age, FIFA and Mirror's Edge franchises, among others. BigPoint recently kicked off an international distribution deal with the Play4Free brand, launching nine localized versions of strategy title Lord of Ultima.