It is yours!
Scottle:
It sounds like you are worried about losing the car to you father by virtue of his name being on the title. But worry not because the car is yours, lock, stock, and barrel!
On your 17th birthday, your father made what is known in Property Law as a valid inter vivo gift, which makes the gift irrevocable and the title of that car has since been vested in you even though your father holds the actual piece of paper.
A valid inter vivo gift took place because (1) your father (the donor) was competent of mind when he made the gift and (2) that he fully intended to make that gift, (3) the gift was then delivered by your father to you (the donee), (d) which you accepted and, (e) the gift was immediate and absolute. Once delivery and acceptance of an inter vivo gift occurs, there is not taking it back.
Now, your father's failure to convey to you the certificate of title may on the face of it bring doubt as to your bona fide claim for ownership, but you can cure that by showing a few other evidence proving your father's donatives intents.
I am not going to bore you with details of landmark cases that have all come down on the side of the donees; suffice it to say that the car is yours and yours to keep and keep on enjoying it.
fredrikklaw