This is rather interesting. In Europe they are working on technology that would make cars into trains - basically. What happens is there are computers, sensors and all sorts of gizmos which link up the cars. Obviously the car in the front is the "lead" and all the other cars follow that car. So, the cars following just sit back and relax. Apparently this is going to be safer, more economical and cut congestion. This is already in the testing phase, so if successful it should go into production rather soon. They better keep the actual computer human input part simple - because you might just go "ah, I am linked up to the lead car now." You let go, and all of the sudden your car is in crushed up against a tree...
Check out the demonstration right here:
http://volvo.qbrick.com/index.aspx?cid=2&mode=3&mid=564
