Yes, they will voluntarily reposess your vehicle (in most cases).
BUT....
you will have some major problems:
1) You will owe the negative on your note.
2) You will owe the costs of the repossession (towing, legal fees, transfer costs, titles, etc.).
3) You will owe the extra costs (auction costs, etc).
So, lets look at an example:
You owe $5000 on your car note.
They recover your car and sell it for $4000 in auction (you owe them $1000).
The costs to reposess your car are $400 (you now owe them $1400).
The costs to sell your car at auction, etc. is $600 (you now owe them $2000).
You no longer have your car, you have a hit on your credit report, AND you still owe them (the car lender) $2000!!!!
I suggest you sell the car, even at a small loss and pay off the car instead of letting it get repossessed.