Best Hardware you are looking for:
3 large monitors,
A gear stick (
www.thrustmaster.com/products/th8-rs) (unless they are driving auto which this can be set to sequential),
Proper pedals with a very high rotational steering wheel (Like a real car) (
www.thrustmaster.com/products/t500rs),
Track IR pro 5 (To track their head position so they don't have to press buttons to look left and right) or you could make an LED cap for some free software called "FreeTrack" which would be much much cheaper,
You will need a Handbrake (E-brake, parking brake) but I cannot find any companies that sell ones that will work for a computer game (I made my own out of knex),
These are the most expensive things on the commercial market. But you might be able to find a company that makes proper car simulator parts.