1. This is a breech of agreement and the cinance company can pursue this through the courts ro recover their money. I don't think this is an offence per say but a deformation of character. You details will also be registered with credit agencies for default of payment
2. No. It is the duty of the purchaser to ensure that the item (in this case the car) is clear of any loans secured on it. In this case, the car can be taken away from the new owner.
I am sure someone will be online soon to explain in more detail