Technically it still belongs to the last registered owner. The state will issue the last owner with a first and final notice (they will have 4 days to remove the vehicle) IF the vehicle is not removed:
if the Vehicle is less that $1000 in value it is scrapped
if the Vehicle is more than $1000 it is sold and Auction to recover the councils costs.
If you take a car that has been abandoned you can be done for theft. You have no claim to an abandoned car.