How to fill out the Private Car Sale Contract Template? Use our private car sale contract template to create a legally binding contract between the buyer and seller of a vehicle.When buying a vehicle or equipment for your business, use this Vehicle and Equipment Purchase Agreement to protect yourself from unwarranted liabilities. 1. Enter the car details including make, model, and registration number. Below, we've outlined the steps and forms required for how to sell a car in the state of California so you can sell your car quickly for the most cash. In California, there is no authoritative return policy on used cars. Once a purchase contract is signed, it is difficult to reverse it. You'll need to sign a residential purchase agreement, make an offer, possibly put down a deposit, conduct inspections and close the sale. Discover the ease and convenience of using Costco Auto Program. Get started on the purchase or lease of a new vehicle or learn more about buying a used car.