|720+ is generally considered prime, 668 is not bad but it is also not great. Luckily, Nissan offers the same money factor to tiers 1-3 if you have a credit score of at least 620. Though the dealer will probably claim your credit score is not high enough to get the best rate, it in fact is.
The rate on the Touring model is .00240. The residuals are as follows:
36 - 57% 39 - 56% 42 - 54% 48 - 50%
This is for 15K miles/year. For 12K add 1% for 36-42 mos and 2% for 48 mos.
The acquisition fee is $550.
Now, these numbers are if you finance it through Nissan. Other finance companies (like Chase) may have different rates, residuals and credit score requirements.