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There's no reason not to ask for the extra couple grand that you need. Not going to hurt anything and I would put in the info for the exact car that you are looking at. If they don't budge, I'd consider using one of your CCs to pay for the extra dollars you need.
Glad you are in a position to afford your new car.
A couple of things to consider:
Your Chapter 13 was finalized 2 months ago.
And, you were insta-approved which is great.
I doubt you are calculating your DTI correctly. The bank will look at rent/mortgage (still debt), student loan payments and various other obligations including the anticipated payment for the loan you are applying for when making the calculation.
How long have you been at your current salary/job?
PenFed is easy to work with and think you should consider calling them and providing additional information. It may help for them to know which car and what the total cost for the car will be. Also, let them know you plan to put money down, and it sounds like a significant amount. That will likely help your case as well.
Also, a lender may get spooked if they know you will have $100 left in your account after making a purchase like this, being able to show that you have working capital for your home budget can also be a positive thing (and needed for a mortgage).
And I have to ask, what car is it you are looking at?
Good luck and let us know how it works out.