Impact On Credit Score?

CREDIT KARMA AND Others like them have a credit score predictor when doing certain things. Try that. When I paid my car off, scores were not readily available but it made little difference because I already had credit cards and paying less interest was more important to me than a slightly lower but still good score.

If your rate is 2.99% its not as big a deal as if you are paying 6-12% or more.  But if you have the money, even a 2.99% guaranteed return is a good bet. I have money sitting in a 1% savings account and most pay closer to .60%. Thats 6 tenths of 1%.

Zero.

Maybe a decline depending on how long the car loan has been open.

Your score increases when you maintain positive credit behavior.  Paying your loan as agreed each month.  Paying it off stops the monthly payments.

If you have had the loan for less than a year, it's possible that eliminating this loan may actually hurt your credit.

STILL unless the rate is close to 0%, you have saved interest money which is a GOOD THING TO DO!!!

Congrats!