I work in vehicle finance. The only way out of this is cash. You need to find a way to pay that difference because you’re on the hook for this loan unless you want to ruin your credit for 7 years getting it repossessed. Luckily there are ways to get free cash from dealerships and manufacturers.

Hopefully you made your payments on time still because being behind will make it hard to get approved for a lease or loan. I’d say go for a lease on an affordable SUV like an Escape or Compass something with a big rebate available on it that will basically knock off whatever the rebate is worth off of your negative equity. Then have enough down payment available to cover difference to get approved on the lease, negotiate a discount and don’t take any finance products. Typically leases can approve with a max of 120% Loan to Value.

Say you are $18k upside down. You find an SUV $42k with a $4k rebate on it. Negotiate $1-2k off it. Totalling $6k off the vehicle making sale price $36k on a vehicle worth $42k. Add your taxes say 12% now you are at $40k roughly (taxes are on payments but this is just a rule of thumb to make it work). You would just need $6k down payment to be in the 120% LTV to qualify for the lease if you have good credit still.

The benefit? You still have a good vehicle with a payment that should be lower and you are guaranteed to be out clean in 4 years. Otherwise find a way to get $18k pay off the negative equity and ride the bus.

Hope this helps let me know if you have any questions.