Your car loan is not like a credit card. Your payment will stay the same until the loan is paid off.
If you want to get the loan paid off faster, don't just start making extra or larger payments. You should make your monthly payment and then if you can send some more make sure they apply it ALL TO THE PRINCIPAL. This will really make a difference in how long it takes to pay the loan off. Call your bank or from whomever you borrowed the money for your car to find out exactly how to "pay down" your principal.
No, paying off your loan early will not hurt your credit.
