ventouxbob:
Yes, putting it on a credit card is a risky proposal for an average Joe. And this only works if you have a credit line 3 X the amount you want to borrow. Otherwise, you are correct your credit score will be compromised. Ideally you spread this $16,700 amount over 2 credit cards with $16K limits each. So balance on each credit card would be ~ $8350K. Then you use your 3rd credit card for regular purchases.
Backup plan is to refinance the car.
You can refinance used cars 5.29% for 80% of new car value up to 48 months with limit of $100K see
https://www.penfed.org/productsAndRates/loans/vehicleLoans/usedAutoLoans.asp
I should warn you, PenFed have very strict guidelines, they reject liberally
I paid off my first new car in 12 months worth 1/3 my gross salary. Used zero interest rate credit card transfers, back when there was no cash advance charges.
You are in good financial shape. Keep saving and be sure to invest in a Roth IRA, if you are below the income limit. If not you still can still contribute to a taxable IRA (not get tax deduction) but rollover to a Roth IRA in 2010 or use it for a down payment on your first home.
Leasing is only advantageous if you have a cash generating business to deduct the leasing expense. Or you work for a car manufacturer like Toyota or Mazda. They have great lease rates which include maintenance and GAP insurance. One employee can lease up to 4 cars, for family/friends so start looking for friends in the right car company!