Asseto Corsa is available on Steam now. Its actually an "Early Acess".
The first build of Assetto Corsa includes the main structure of the game and 8 classes of cars for a total number of 11 vehicles, with the aim to guarantee just from the beginning the chance to enjoy the dynamic model of the game racing with different kind of vehicles.
As part of the early access program, an update with new cars, tracks and features will be available every two weeks, adding new contents and improving the existing ones.
All the vehicles and tracks will be released in a level of completion close to the final one, with the aim to deliver, starting by the first version, an enjoyable and satisfying simulation, featuring cars and tracks reproduced at their best, with the exception of unknown minor bugs that will be fixed and polished in time for Assetto Corsa 1.0.