I'm in the process of buying my first car. I've narrowed it down to a few cars in the $10000 range. My question is: What kind of offer should I be making if I'm buying from a dealership? 10% below asking? 15%? 20%? And are there any other specific things I should ask for? I've heard asking for a full tank of gas and new tires are among the biggest. If it makes any difference, I'm looking to pay for the car in full.