Negative, this sim is geared to organized, sactioned, class racing. Yes you can run a single player career if you want. In that you start with a base car and s you race you earn points that can be spent to add upgrades to the car. These upgrades move you up in class.
Now while that's there, it is not the main focus nor the strong point of this game. The main focus of the gane is to allow online head to head racing in organized leagues. These can be leagues based on one class of racing with championships, etc. Or they can be more informal leagues that may run more than one class or type of vehicle and are more about the comaradarie of club racing than winning a championship.
You do get to set up your car by adjusting springs, shocks, gear ratios, brake bias, tire preassures, etc. In certain classes of racing some setup features are limited so that the cars are on a more equal footing to make for closer racing.
Here's a couple of forums you can look at to get an idea of what rFactor is about. You'll need to scroll down to the rFactor specific sections.
http://www.thepits.us/board/index.phphttp://www.rscnet.org/mambo/Hope this helps.