In New York State it's kind of sketchy?
My dad has an S6 avant and it only has a rear plate ( the dealer only got one plate, our big ugly plates would look terrible on the front of that car) The law here reads that it is "recomended" by the DMV and law inforcement that you have both front and rear plates. Which would make you think that it's not mandatory, then they go on to say if you don't have two plates you could get up too a $200 fine. Go figure! Havn't had any problems yet with having only the rear plate!