C1Yx: Very similar in size to the current Lambda program-
C1YC = NG Chevrolet Traverse
C1Ux: Smaller than current Lambda:
C1UL: Launch Cadillac XT5
C1UG: GMC Acadia
C1YL: Cancelled Cadillac utility
E2xx: NG Epsilon platform, midsize up to full size
E2SC: Launch Chevrolet Malibu
E2LB: NG Buick Enclave
Presumably, the E2 program uses "S" as the 3rd character to denote short or standard wheelbase, and "L" as the 3rd character to denote long wheelbase.
E2UL: Fullsized Cadillac utility
Escalade replacement or supplement?