I wouldn't expect them to be very functional. I would assume they are purely an exercise in styling and much less about actual aerodynamics. I could be wrong though. The rear 'diffuser' I can almost guarantee is completely non functional. It doesn't follow any of the basic principals of aerodynamics.
They are 100% for aesthetic reasons only.
If anything, it may actually increase drag but it wouldn't be noticeable, as that any difference would be minute. Needless to say, I still have the front lip and side skirts because they look good (to me.)
IMHO ... an important mod in the aesthetically **pleasing aspect of individualism to any car we are enthusiastic about is items like *side-skirts,air dams,spoilers,"BIG WHEELS''.... etc.
As for true or any real potential to do anything.... most not likely. On true Road Trackcars most of those items are generally test and adjust as-u-go and every different day as well TRACK and environment conditions can have you running around the car making adjustments all day long. Besides not all of use have a wind tunnel we can rent for a day to test parts nor do many of us attach dozens of different length dowels with ribbons attached and have someone video you from another vehicle at different speeds to see were and how the air flows over target areas of the car.
For street use sometimes (almost never) you can add something like a factory or aftermarket skirt and then after setting a DELTA carefully watch you MPG,vacuum, ignition timing (to mention a few)and see if there were any effect changes either positive or negative.
Really it is easier to just *install-um and have people like and thumbs up on um!:grin2:
Oh and for my LOOKS upgrade I have this set and a few other things I am doing to the body...why because **