BMW faces constant challenges from Mercedes-Benz, Audi and Cadillac and took no chances by refreshing its entire 6-Series lineup at the 2015 North American International Auto Show in Detroit.

The BMW 6-Series showcases two variants – the 640i and the 650i that consist of a coupe, convertible and Gran Coupe sedan, which all received exterior and interior enhancements. New additions throughout the range of vehicles include a change to the typical kidney front grille, standard new LED headlights, and revised rear and front bumpers.

Inside, you will find an enhanced head-up display that is more intuitive. The all-around luxury feel has been refined with higher quality materials used including a two-toned leather seat option available.

Under the hood, the 640i's are all powered by a twin-turbo inline-six that generates 315 horses and 330 lb.-ft. of torque that's mated to an eight-speed Steptronic automatic transmission. Jumping up to the 650i – they receive the twin-turbo V8 that tops out at 445 hp and 480 lb.-ft. of torque.

All of the 6-Series vehicles have improved fuel economy and can be driven in Eco Pro mode with start/stop technology for greater efficiency.