GM says in a statement that it "in no way" is discouraging anybody from using the name Chevy. The internal memo was part of an effort to develop a consistent brand name as it tries to broaden its global presence.
There have been many pop culture references to Chevys. Perhaps the best known is in Don McLean's "American Pie." Its signature sing-along chorus begins, "Bye bye, Miss American pie, drove my Chevy to the levee but the levee was dry."