It appears the U.S. Treasury has little confidence in GM, ordering the automaker today to prepare for a bankruptcy filing by June 1st.  All is not lost, though, as the point of this exercise is actually to make sure the best brands remain salvageable. Car guys can relax.  Chevrolet, which makes the Camaro and Corvette, and Cadillac, which makes the CTS, appear to be on the safer side of things.  One bankruptcy plan would split these brands into a separate company ...