[Carl Abrams]

Does anybody know what Exterior Color: AG1 means?
Is that a combination of exterior / interior colors?

Actually, TAP is the Exterior color code for Autumn Green, if you ever need a touch-up pen. Yes, I know that makes no sense. D4S is Crystal Black, K1X is Crystal White

The code you reference is the interior / exterior combination
AG1 means Autumn Green, with slate black cloth / leather interior.
AG2 is Touring (Napa Leather)
AG3 is Ivory cloth or leather
AG4 is Startex

And just to show how totally consistent they are (NOT), Black is CB3, CB4, CY7, CBL, and CBS. White is W17,W2P, W5P, WH5, and WHC.