Getting the new state to accept you as a new resident is easy, its convincing the Ca FTB that you actually moved out of Ca and severed all ties to Ca, before buying the new vehicle that's important. As the law says, your domicile doesn't change until you have established the new one, and moving out of Ca is part of establishing a new domicile state.
When I retired and began fulltiming as a SD resident, I was on my way out of Ca the hour after collecting my final checks and gold watch. I had already sold my Ca house and extra car. I bought my motorhome years before leaving the state, so I didn't have that complication. I had switched all my accounts to my new SD address before the final day. I filled out the Ca DMV forms to notify them that my current Ca vehicles, motorhome & toad, were being transferred to SD. At the end of that year, I filed a final Part Year Ca Resident tax form using my new SD address.