Can a civil judgment result in the repossession of a car that is co owned?

If the civil judgment is due to not making payments for an auto loan on the car that is in question, then yes, that car may be repossessed as a result of the judgment.

If there is a judgment against both owners of the car (i.e., if the co-owners are both listed as defendants), then the car is considered an asset and may be repossessed unless there is proof that the car is required for one or all of the co-owners to earn money in order to pay the judgment.

If there is a judgment against only one of the owners of the car (i.e., if one of the co-owners is listed as a defendant, but ANY of the others are not), then no, the vehicle may not be repossessed.