Also, other car manufactures actually change their prices all the time based on cost of materials, shipping, etc. The Dealer will change the price based on inventory space, cost to hold, etc. You just don't see it as much because it is hidden behind Dealership "Deals" and "Promotions" that come and go.
Traditionally, it has always been the best to buy a vehicle at the end of the year, when the dealers are trying to make room for the next "model year".