INSPIRED BY THE RAILROADS? Cadillac's latest slogan is "The New Standard of the World." (Once upon a time, The Pennsylvania Railroad was The Standard Railroad of the World. Despite carrying a great deal of the men and materiel to win in Europe, the carrier dropped the slogan in 1946.) A commercial for the CTX sedan claims its shape is derived from a drawn arrow. (But unlike Hiawatha, the CTX did not go forward with such fleetness that the arrows fell behind it. Just as well, no matter how stylin' the car is, it is to a train as a pop can is to a car.)