Make sure you maintain a low debt-to-income ratio by avoiding large purchases. Because a large payment and balance can cause a significant decrease the amount of home that you can buy.
Depending on your income, a $400 car payment can decrease your home purchasing power by many thousands of dollars. If you are needing a car, then try to wait until AFTER you get the keys to your new home. But if you need a car before the home, then try to purchase an inexpensive one, and pay cash.
It is important to analyze your goals for homeownership. What sacrifices are you willing to make to stop renting and start owning? By putting off the large car payment for a little while, may allow you to get into your dream home now.