Funny enough, on our way to visit my brother in Toronto, we stopped at the Force Dynamics headquarters in upstate New York to check these out in person! My father was interested in the flight simulator version, which is about 85% similar to the driving version and can be converted back and forth with a little bit of work. The video demonstrates the motion much better than I could try to describe — it needs to been seen (ideally felt) to believe.
I drove a few laps in Live for Speed and RFactor — the sim itself supports lots of different games, but these two strive for realism, where many of the others are more fantasy/arcade style. The neat part is the games are completely standard, so all the online racing features work, you can race real people all over the world, as well as upgrade to newer games and PC hardware as the software improves. Apparently one of the tricks is you don’t tell anyone you are playing with that you are sitting in a simulator that has such dramatic motion or else you’ll get bumped without remorse.
The other neat thing about a simulator as compared to driving in real life is you can drive cars that you’d never be able to drive in real life on tracks that are impossible to get on or even don’t even exist anymore. For instance I drove a 1955 Mercedes F1 (Wikipedia link: W916), a beast of a car which won the world championship in ’54 and ’55 (Mercedes got out of racing for 30 years after a crash killed a driver and 82 spectators at Le Mans) on the legendary and dangerous Nordschleife.
For those not willing or able to accommodate a 750 pound simulator in your home, may I suggest something along Jeff Atwood’s rig?