Pretty similar to a private transaction, the seller signs the title over to you. For in state, you would then deliver the title (mail or in person) to PenFed. If you fail to do so, they may raise your rate or simply cancel the loan and send a collection agency your way. They have quite a bit of authority with your signed loan agreement.
For out of state, it is even easier. When I registered my vehicle at my DMV, I simply indicated who the lien holder was and they were supposed to mail the new Title directly to them. You never get the title back until the car is paid off.
I happen to know this because the ever so sharp Virginia DMV messed it up and mailed the title to me instead. Now I need to re-mail it back over to PenFed
More than likely there will be some weirdo mark on any future Carfax report that is ever run. Oh well, maybe they will google this thread (psst - its on VIN JH4NA21621T000002).