Alongside the standard 8 Series coupe, BMW will drop the top of its newest vehicle in the form of the 8 Series convertible. The rendering pictured here, using spy photos and teasers to work with, gives us an idea of what to expect. BMW's classic 4.4-liter biturbo V8 should be underhood, delivering somewhere in the neighborhood of 630 horsepower (437 kilowatts).