A lien is only valid while there is a collateral attachment registered to a vehicle or a thing. When you borrow money to purchase a vehicle, the lender places a lien against the vehicle as protection for their monies loaned and in anticipation of you honoring the loan contract. A mechanic's lien or personal property lien can only be placed when there is money owed on a completed service. Once the value of the lien has been cleared either through the completion of a legal contract or through a final payment of an amount owed, there can be no lien. The dealers will likely argue that they have an "interest" in the property, but my guess that without some monies being owed, their argument would be laughed out of the building.
The real issue to the lien, especially if you are not "flipping" the car, is that liens tend to get forgotten as they are not in your face everyday. So five years from now you go to sell your C8 and find out the the lien is still on the vehicle (remember only the lien holder can remove the lien, or the courts through a court order) and your sale goes upside down. The Carfax info for example would not tell the buyer the amount of the lien, only that the lien has been registered against your C8. Poof, your sale has just become very complicated.
Under no circumstance should you accept a purchase with this type of lien on the car. Understand that if you are financing the car, the bank will have a registered lien but those liens are pretty straightforward to clear.
As a reference:
Personal Property Liens – Register an interest