The bank takes back the car and sells it at auction. Lets say it takes them 6 months to sell the car. If its damaged they will fix the car first. So lets say it takes 5,000 to fix the car. They sell it for 2,000 at auction.
So now the bank is into the car 13,000 (5,000 to fix it and 8,000) for what you owe. They can also add on attorneys fees and court fees and lost interest so lets say they are now into it 14,000. Trust me they can add it up fast. So now the bank says they are into this car 14,000 and they sold it for 2,000.
You now owe the bank 12,000 for a deficiency judgment. They dont even have to go to court. Instead of owing the bank 8,000 for a car you have, you now owe them 12,000 for a car you dont. This happens all the time. Once they have that judgment the law allows them to garnish your wages, take it out of your bank accounts etc. That 8,000 doesnt go away, it will skyrocket.