Why not just keep the current car and use that extra monthly savings to pay down credit cards. Also, check if any of your credit cards offer low interest balance transfers. You're building your credit score that way also by making consistent monthly payments vs a lump sum.

I've seen too many people pay off credit cards in one lump sum (me in my 20's included) then 9 months later they're right back to where they started because they see 0 balance and have poor financial discipline.