Vehicle repo timing

[coman]

Hi, I voluntarily gave a car back to a finance company yesterday with the intent to see it go to auction and a resulting deficiency, hoping to add the deficiency into a Chapter 13 to be filed at a later date. Is there anything I may gain or lose by this kind of timing or tact? The car as far as seeming book value is equal to the its loan while the true auction value due to condition and economy is much less. This second car is not a necessity and I thought adding the eventual deficit in unsecured creditors would be better then having to pay the same amount as the current loan (due to inaccurate book value) in a Chapter 13 plan. Thanks