Need for Speed World does the honors by surpassing five million registered users. The free-to-play racing MMO from Electronic Arts most recently made metrics-related headlines last December when it topped three million registered users.
Gamasutra has the details on the latest milestone and also notes that NFSW is offering motorsport fans a chance to check out virtual versions of actual automobiles from Audi, including the new A1 ClubSport Quattro that was unveiled yesterday.
Need for Speed World is the 15th iteration of EA's venerable racing franchise and the first to feature MMORPG stylings. You can read all about it and download the free client at the game's official web destination.