There are some programs to help people who purchased a car when they had a good job but then lost it due to the bad economy. For low income there isn't really much you can do because having a car is a luxury not a right.
public transportation is your best option if you have low income. Many dealers offered excellent rates with no downpayment. It's easy to think you can afford a car you actually can't. be careful, that's how alot of people got in trouble in the housing market. People need to start buying in their means and not pretending to have money.