Going through the comments, I guess there is an answer in the comments, and noboday has put it. So just putting up an answer.
The Black book value of 2004 Impala [highest trim model] is about $7000. Hence Banks will not lend you $12,000 secured loan on it.
Plus as you mentioned No Bank is allowing you to apply for a loan, Banks have their own policies and you cannot force them.
- Try getting a loan from friend / relative, if they agree to it, offer a rate of 6-7% to them, this may enable to you pay off the loan faster.
- Check if you are getting a personal loan at cheaper rate.
- See what is the best sale value you can get for your car ... if its close to the loan, you can sell it off now and then buy another cheaper used car at lower interest rate.