When General Motors Co (GM.N) takes the wraps off its new Cadillac CT6 on Tuesday the most important thing about the vehicle could be what is under its skin. The CT6, to be unveiled ahead of the April 3-12 New York auto show, is an expensive car aimed more at boosting Cadillac’s brand image than sales volume. GM engineers are studying variations on the CT6’s multi-material construction for at least four other future vehicle architectures and other models could be derived from the CT6’s “Omega” architecture, Travis Hester, CT6’s chief engineer, said in an interview.