Most people think paying cash is the best way to a good dal of a vehicle. To be honest with you, if you pay cash you are taking about $500 in finance money the dealership calculates into their deal off the table. 99% of the time you will get LESS off the price of the vehcile! Wow!
When you say "I'm paying cash!" you may be shooting yourself in the foot.
Quick tip for fixing that: Pay cash but dont let them know! Here's how!
Work the deal as you normaly would. Talk about PRICE and TRADE IN and don't even ask about interest rate. If they ask you say "I DON'T CARE, WHATEVER"
*MOST* car loans (and the finance guy should tell you upfront) don't penalize for early payoff. Get a loan, if it helps you get a better price, and pay it off, ASAP.