What to include in a vehicle bill of sale. You do need bill of sale.You may want to write up an extra thing that both of you sign to CYA but that's not for the DMV. 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. What documents do I need to transfer a vehicle title? How to Sign Your Car Title in San Jose. We've Compiled a Detailed List with Instructions and Sample Picture of the San Jose Title.