If the value of the vehicle went down and it's lower now than what you owe on the loan, this is called a negative equity situation.
If you trade it in, even for a less expensive vehicle, then you have to carry over your negative equity into your new loan.
Say your Murano is worth $20k but you owe $25 on the loan. You're upside down (have negative equity of) by $5k.
Trading it in for a $15k vehicle, you will have to add that $5k to your new loan. Now you'll be financing $20k on a $15k vehicle. Many banks won't let you do that unless there are enough rebates on the vehicle you're buying to cover that negaitve equity, or unless you have money down to cover it.
How much do you owe on it, and how much were you told the value of it is now.
Also what interest rate are you paying on the loan?
What are your current payments?
What payments would you like to be at?
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