You use the car to make short trips around the area, scavenging materials from places others have abandoned.
Just think of how much of a household you can take in a car, not much.
You use the materials you find for trade, survival and fortifying your house. You join a like-minded group of individuals in your AO for mutual support and defense, those not-like minded will probably leave one way or the other.
You continue to strengthen your position and life becomes a 24x7 quest to survive.
Eta: it might be fun to test my welding skills making abandoned cars into mad max type vehicles
"Our Constitution was made only for a moral and religious people. It is wholly inadequate to the government of any other."
-John Adams, America’s Second President