Greetings from OCS stand down.
So, I believe this may be dependent on the OCS director but for those of us on stand down, we are NOT allowed to use our vehicles unless we're on leave. In other words, unless you live close to the area (no more than a 12hr drive), know you'll be assigned to stay in NS Newport, or simply have no place to store your car, you're better off leaving your car behind. Driving out here to just use your car during Senior CandiO phase is not worth it.
If you still decide to bring your vehicle, car starts are not guaranteed and it's up to your class team on how generous they want to be (our first car start was the weekend we finished Indoc Phase and we ended up getting car starts almost every weekend thereafter, but other classes weren't as fortunate).