At one time I was a car salesman. I know a few of the tricks. I didn't do it for very long, but a little research will tell me what is and isn't a good deal. The important thing is to never accept a first, second, third, or fourth offer...

The best time to buy a car is after the 20th of the month. That's when they're worrying that they might not hit their quota. If you wait til the last 3 days, they might have already hit it, or it might be too far out of reach.