[hector]

how does bmw, or any other manufacturer, decide what displacement engine to choose when by, for example, adjusting boost in a turbo app., they can easily arrive at the same total output for 2 engines of different displacements? for example, take the 320i in u.s. spec putting out 180hp/200ft-lbs, output that the 1.5l 3cyl could achieve if it's specific output were the same as the 2.0 4cyl in the 228? there are i'm sure pros and cons to each method, some of which may be marketing related as opposed to technical. specifically, with weight reduction a priority, wouldn't the smaller mill save substantial weight?