Advice! have a problem buying a car?

my sister is a college student and im helping her buy her first car. so we need to get the best price out the door for a mazda3. msrp on it is 16,785. the dealer seems nice and calculate the cost and the price including tax will be 18,500 . can i still mark down the price and haggle with them? can you ask to go below the marked msrp? or the asking price?