In 2013, BMW introduced the 4-door 6-Series Gran Coupe to provide a stylish alternative to their 5-Series and 7-Series luxury sedans. The Gran Coupe is similar in size to the 5-Series sedan but lacks some of the interior volume due to a 3-inch lower height. BMW identifies the seating configuration as "4+1" which means that it's optimized for four passengers, but can carry 5 in a pinch. Like all BMWs, model designations mirror their powertrains. The 640i equips a 315-bhp turbocharged inline six-cylinder and eight-speed transmission. The 650i ups the power level to 445-bhp with a 4.4l turbocharged V8 engine. All-wheel-drive is available on both the 640i and 650i. Like other BMW model series, the ultimate performance model is the M6 Gran Coupe which equips a higher-output 560-bhp 4.4l V8 engine mated to a six-speed manual or 7-speed automated manual transmission. The Gran Coupe carries a hefty price premium over the 5-Series sedan with prices ranging from $78,000 and up.