Used Car Financing Question! I Need Help!?

hey guys, if anyone knows about financing please i need your help. My sister is trying to get a car, a 3-series sedan and the vehicle costs about 23,000. The guy at the used car dealership said that with a co-signer, who she has, my dad. My dad has about 780+ credit score and he wants to put $5,000 down. The guy said with a 72 month payment plan it will be 12% interest rate. Doesnt that sound alittle too high? even with my dad co-signing for her. Btw we live in CA if that helps.