If you've made it to this stage of the car buying guide, then give yourself a big pat on the back! This is what I consider to be the absolutely top car buying tip found throughout this site.
Do not buy the car the first day that you see it and/or the day you negotiate numbers. Ask the dealer to borrow the car for the night.
You'll notice this step comes after the negotiation and there is a reason for that. Let them show you all the numbers before you spring this on them, because you want to be able to analyze the numbers from the comfort of your home.
In addition, you'll want to wake up to the car in your driveway to see if you still have that "I've gotta have it" feeling in the morning.
Follow this ninth step in the car buying guide and you're practically guaranteed to eliminate buyers remorse.