Roosvelt

That happens when you don't have the DLC unlocker files, aka, you are not a returning player.
If that way does not work still, that car is probably blacklisted, but i think a lot of people still have it in their garage.

The Roosevelt only available during the Feb 2014, so if you missing out on it then the only way you be get it is to cheating into the game. And even doing that now to this date, the car not saving after you leaving the session.

I still have the roosevelt i use the freeyoo menu