I put a deposit on a car on a Saturday and went back to negotiate on Monday. It was midyear on the car and I looked what the same year car was selling for used. I split the difference and went back on Monday offering that price. The salesman got up and said he had to talk to the manager. I told him when he came back I only wanted to hear yes or no, no BS, no counter offer. He came back and threw the keys on the table and scowled at me. I felt pretty good about it.
What used value did you use, same year or the previous year?