If I have a judgement filed against me from a credit card with a collection agency filing the judgement, can the local sherriff dept. repossess my vehicle that is finance and sell it at an auction?

If it is your only way to get to work I doubt they can because even if you file for bankruptcy they have to take that into consideration. Unless maybe the car is directly related to your credit problem some how.

Normally no, in most cases it would be part of the exempt property, but again, in some areas lets say you bought a 40,000 car instead of paying your other debt, I am not sure a judge may not rule in their favor if they made a motion for it.

But this will vary greatly from state to state in the US.