Legal Question in Real Estate Law in California

Well, you just said it yourself: "her car."

Actually, your legal situation is this: The person whose name is on the DMV title is the "legal owner" but is not therefore necessarily in all cases the person who may claim a superior right to be the owner. If you can prove to the satisfaction of a court that the car was given to you as a gift, the judge could order the "legal owner" (your ex) to sign over the title to you.

The law of gifts is generally that when X turns over the possession of property to Y along with a written or oral statement that a gift is intended, and Y accepts the gift, ownership is transferred.

In this particular situation, it seems to me that you are going to have a difficult time proving the intent to make the car a gift to you, because when the car was purchased, she took and kept title in her name. This is inconsistent with intent to make a gift. If a gift were intended, a judge would probably say, she would have put title in your name.

More likely than not, she only intended for you to have the use of this car so long as that was her pleasure, and upon your breakup (or not needing the car for whatever reason), she was to recover possession and use.

So, her keeping the car is probably legal, but if you could prove a gift, you would become entitled to possession and ownership, but not before.

The car belongs to whoever is on title. If you want to try to sue to claim an interest in it, you can.