BMW’s new M850i xDrive Convertible just made it easier to forget the 6-Series. The M850i’s twin-turbo V-8 still displaces 4.4 liters, but the engine was redesigned from the crankcase up and now produces 523 horsepower and 553 lb-ft of torque. At the base price of $122,395, the 2019 M850i xDrive convertible is more than $20K pricier than the equivalent 2018 650i xDrive droptop.