In most cases, the dealer will give you an offer for what he thinks he can sell the car for in the local market (generally through another used car dealer) or at an auction. Many times, the dealer will call multiple used car dealerships and see what the best offer for the car is. He will mark it up a little and go from there. Basically, if the dealer doesn't think he can get much for the car, he won't offer much regardless of how good the condition is.