The term "four-door coupe" has been insinuating itself into the automotive lexicon ever since the 2004 Geneva debut of the Mercedes CLS sedan, and BMW is the latest to add to the gathering ambiguity of a word that once referred to two-door automobiles. Making its global debut at Geneva, the Gran Coupe adds a four-door BMW rival for the CLS and the Audi A7. The initial offering is powered by the same 315-horsepower 3.0-liter turbocharged inline six-cylinder that propels the 640i coupe. V-8 versions will appear later. U.S. pricing for the four-door coupe will be higher than the two-door, starting at close to $77,000.