You *might* be able to get into the priority screening line with the GM card alone but I would be highly surprised. This is the same idea behind folks in other threads who have discussed purchasing DM tags off of eBay. This is, of course, assuming that a single priority line serves all terminals and all airlines. If the airline you are flying uses a different terminal you are completely out of luck. The truth is that the line attendants have typically been trained to look at the BP, not the elite status card (regardless of airline). My guess is that you won't be getting into the priority screening line.