Check around for the best rates. 18 months ago when I bought my Tundra pickup I called up my credit union that I have used for years and got a 2 3/4 rate. I told the dealer that I would take care of the financing thru my Credit Unions and he asked me what is the rate. I told him 2 3/4 percent and he asked if 2 1/4 percent would be better (dumb question as the answer is yes). They worked thru another credit union so I made a token deposit of 5 bucks and went with the lower rate. A person just never knows. I met a few months ago a banker and their rate was even lower (special I think). When I replace my Prius this fall I will check around and see what goes. A couple of calls to to credit unions and banks should give me a good idea.
Maybe if you get a good rate on your own and then the dealer might lower it who knows.
Flagman