I was told by a dealer after calling about an “in transit” vehicle that GM showed on the corporate website for the dealer that GM requires them to keep it listed on the dealer website until the vehicle has been delivered and paperwork has been signed. When a dealer says it is “sold” already that just means someone has put down a deposit on it already. Even though it’s highly unlikely, there is a chance the deal doesn’t get done once the vehicle is delivered for a number of reasons (customer doesn’t come for pickup within a set timeframe, financing falls through, customer changes mind once they see in person etc.). Don’t bash me if this isn’t 100% true. It’s just what I heard and it seemed to make sense.
TL;DR
GM requires the vehicle to be listed on a dealers website until the vehicle has been delivered and a customer has taken possession of the vehicle.