I can't understand how you figure to cut down your budget when you still have 4 yrs of payments and want to add another car. Trade the Nissan up on a newer model will work, trade down on another used car will most likely never work.

With the information you provided I can't read into the financial end of it. Here are some personal questions that if you care to answer then email me to keep it private.

1,,, you got a balance of 48 payments ? at what rate and what are your payments.
2,,, adding another car where would you like to be at in total payments ?
3,,, are you thinking to roll both cars into one loan to lower payments ?