How Buying a Car Reduces Your Purchase Price For example, suppose you earn $5000 a month and you have a car payment of $400. Using an interest rate of 8.0%, you would qualify for approximately $55,000 less than if you did not have the car payment. Even if you feel you can afford the car payment, mortgage companies approve your mortgage based on their guidelines, not yours. Do not get discouraged, however. You should still take the time to get pre-qualified by a lender. Next, you contact a loan officer to get prequalified for a mortgage loan. You state your desired price and how much you can put down. You provide your income and may even supply pay stubs and W2 forms. The loan officer methodically crunches the numbers (by telephone, in person, or even over the internet). However, if you have not already bought a car, remember one thing. Whenever the thought of buying a car enters your mind, think ahead. Think about buying a home first. Buying a home is a much more important purchase when considering your future financial well being. Do not buy the car. Buy the house first.