In a Chapter 13 bankruptcy case filed in Oregon court you used to have the option of stirpping the lien of the car.  Basiaclly this means if your car was sitting in Portland, Tigard or Beaverton Oregon and you owed 10,000 on it but it was only worth 5,000 you could take the car down to its present value and lower the interest rate.  For the most part your bank couldn't object as long as the values were fair.  

After the bankruptcy law change is 2005 in Oregon, whether its Portland or Eugene Court, the law to stip these liens are tougher.  Now you need to own your car a total of 910 days, about 2.5 years in order to go through this vehicle lien stripping process.  You still get the benefits of the process and your Portland or Beaverton bank branch cannot stop it.  That said, it sometimes took the ability to lien strip your car and the reduced payment in order to come up with a Chapter 13 plan payment that would work.  Since now you need to own your vehicle a certain time it can make this tougher and may possibly make your Oregon chapter 13 plan not work.  As with everything else make sure your talk to a good bankruptcy lawyer in your town (Porltand, Tigard, Beaverton or Willsonville) before you decide on a path to take.