If both signatures are required, and one owner is not available to sign the title, there are a few options:
* The non-signing owner can sign a power of attorney, giving the other owner the authority to sell the car on their behalf.
* The non-signing owner can send a notarized statement authorizing the other owner to sell the car.
* The non-signing owner can surrender their interest in the car to the other owner.
In some cases, it may be possible to get a court order to sell the car without the signature of the non-signing owner. However, this is a last resort, and it can be expensive and time-consuming.
It's always best to try to get both signatures on the title when selling a car. If that's not possible, talk to your local DMV to find out what other options are available.