You are shopping for a car and read the following advertisement in the$$ newspaper:

$"$Own a new$$ Spitfire! No money down. Four annual payments of just $ $16$ comma $000."$

You have shopped around and know that you can buy a Spitfire for cash for $ $54$ comma $400.$ What is the interest rate the dealer is advertising$($what is the rate that equates the PV of the payments to$$ today's cash price of the$$ car$)?$ Assume that you must make the annual payments at the end of each year.