The Mercury Grand Marquis is a full-size rear-wheel drive sedan sold by the Mercury division of the Ford Motor Company. The nameplate has been in use since 1975 and has been a separate car line since 1983. It is essentially Mercury's version of the Ford Crown Victoria with which it shares its Panther platform along with the Lincoln Town Car. Since its introduction, the Grand Marquis has only been available with a V8 engine, and with features such as 6-passenger bench seating, it remains one of the last "traditional" American full-size cars still available for retail sale; it has even taken the place of its Crown Victoria twin in retail markets (the Crown Victoria has been dropped from non-fleet sales after 2007). As of April 2010, Automotive News reported that Grand Marquis remains Mercury division's best selling model.
Source: wikipedia.org