Congrats on the new purchase. 72 months at 5.9% is a pretty damn good deal.
CORTDD - how about letting the OP do as he chooses. I doubt he posted this to get financial advise from somebody on a car forum. On top of that, how in the hell do you know how long he plans on keeping the car to be upside down at some point in time?
For someone that has but 15 posts, you won't make many friends here with comments like you just made above.