The newer digital slot cars are pretty amazing in what they can do.
You set your car up in the program before you race. Based on what your car is, you get your weight, amount and weight of fuel, speed increase as fuel weight decreases, max speed, braking distance, acceleration curve, and all sorts of things.
So you fuel will only go so long before you have to take a pit stop. It is timed to how long you stay there to how much you refuel. The computer can control several ( I think I seen one setup do 20) cars so you can have huge races while you and your friends control yours, you can do lane changes and and such and have to manage your speed, time, and such. It makes a pretty decent simulation or racing. Also you can lay out a shit load of different cars, from F1 to old muscle cars, depending on what you want to race.
Really cool layout
Now, along those lines, I've been looking into Magracing. That shit looks pretty cool and is coming along but there isn't much you can do with it at the moment. Very limited in the cars you can use and more difficult to build a setup.