Ok, a neat little secret I just found out. If it isn't so secret, I'm going to feel really stupid. Here goes!
Ok, starting from your house thats in Algonquin - the one Roman buys for you - exit your house to the right and turn right at the corner. At the end of the block on the left side of the street, you will notice a fancy car dealership thats indoors. You can actually enter it through the doors or by breaking the glass, and take any of the cars there! They have nearly all exotic models. Its cool because right when you enter the game, you can get an awesome vehicle.