You have $52,400 in the calculator and $51,400 in the post? Which is it?
Try for 16%, but 15% may be as good as it gets. I suggest to hire @Benedetto for the best no hassle deal.
I signed a 3200 miles XC 90 T5 AWD Mom loaner (36/10) for $439mo with $3100 drive off last week. I negotiated a 21% discount. You should be able to do much better on a 4500 miles loaner. I will say this though, I had 2 other dealers who weren’t willing to play ball, so need to shop around.