if you need a tow to make a pass for position, then yes. on public roads it would tend to be a pretty bad idea, an actual draft would probably be illegal.
the hypermiler trend is adding to people who follow way to close on the streets. i drive a smaller car so sometimes i sit back behind a big truck, or at the end of a train of cars. you have to be really close to be in a clean hole so you better be able to out brake whatever is in front of you, and even at that if there ever is any sort of accident having followed so close may play a role in determining responisbility for any part of the accident.
the only time a draft would be benificial in racing would be to use it to accelerate faster than the person in front of you so you could pass them without slowing them down.