No your down payment does not lower the price of the car; but, it does lower the amount that you will finance. A 15,000 car with a 5,000 down payment is still 15,000; but 10,000 is what will be financed and you will pay less interest on 10,000 than you will 15,000; so a larger down payment does help lower the cost. Remember, tax, title and license will be added to the list price of the car.