This information is literally minutes old. I have posted it in my TranZit strategy topic, and I am posting it as it's own topic.
It's possible to unlock a PERMANENT Perk that SAVES TO YOUR PROFILE, but it will only work on TranZit survival. It will not work on any of the other maps in survival, and it will also not work on Grief mode.
The PERMANENT Perk that you can unlock to your profile is Quick Revive. In order to unlock this, all you have to do is revive someone 12, to 15 times in a row, in the same round. If you have done this correctly, you will notice a green poof that will appear over the person you were reviving head. You will then notice that when you revive someone, the word "revive" when reviving will be purple, and it will revive people as fast as it would if you had Quick Revive.
You do not need to buy Quick Revive to unlock the PERMANENT effect of Quick Revive. I will say this again, YOU DO NOT NEED TO BUY QUICK REVIVE TO UNLOCK THIS PERMANENT QUICK REVIVE EFFECT.
Again, THIS SAVES TO YOUR PROFILE, and it ONLY WORKS IN TRANZIT SURVIVAL.