BMW has unveiled the 6-series Gran Coup�. This new four-door coupe will rival the Audi A7 and Mercedes-Benz CLS. The 6-series Gran Coupe joins the existing two-door coup� and convertible in an expanded range of 6-series models aiming to attract buyers who place greater emphasis on outright style than practicality.Stylistically, the Gran Coup� is identical to the 6-series coup� and convertible