NxGTR Sim is the most advanced car performance simulator in the world, with this software users around the world tune their cars to run comparison tests that will help them to choose the right modifications for their cars.
Optionally user can register and add their own car to tests if not included on already provided huge car list.
This program is the not only the most advanced but the only one that can be used for free. There is other options available, very few of them that are so basic that its impossible to get good results from them, other use technology already forgotten by the market like Java Applets, ours use Silverlight the newest Microsoft technology for web development
Any user with love for cars that is willing to learn advanced topics. Users that want to tune their real cars but does not have the knowledge to select the best options for it.