This thread started me thinking... I am not an aeronautical engineer, but I do grasp the basic concepts of downforce, drag (etc) and understand the purposes and advantages of a retractable spoiler. That being said, I can mentally picture the benefits on a coupe, but what about a convertible? In my "brain wind tunnel" I can envision a smooth air stream over a hardtop, but without a top, wouldn't the airflow be so disturbed that any effect would be greatly negated? Or am I just seeing this wrong and that the downforce provided by a spoiler is independent of the slipstream over the vehicle?
I think too much...or if you asked my wife, not enough.
