You're an NFO select? Calm it on down...You'll have TONS of time.
1) You will PCS to API. Why did you think otherwise?
2) If you are coming from BDCP, you'll get a chance to do OPDS--Old Permanent Duty Station--which means that they'll give you around 18 days (Seattle is a long way from Pensacola) to drive to Seattle and back. These days will not be charged leave and you'll get per diem (about $100/day) for that time. This is before checking in at API. If you check in before at least these 18 days are up, you're dumb.
3) Tacked on to those 18 days you can take as much leave as you want, up to another 30 days if you have it. Again, this is before checking in to API.
4) I'm not exactly sure where OHARP fits into all of this--you'll talk to the PSD guys when the time comes.
Look, if your main concern is that your car can't handle it, then you'll have to make that call. If you're worried that it might not be "worth it" to make that long drive three times, trust me, it'll be worth it. You want your car with you at OCS. Let me repeat: you want your car with you at OCS.