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well the aero is interesting in that smoother is better at making the surface slick.
when you make the skin of the car rough (dirt or dimples) you INCREASE DRAG and HARM FUEL ECONOMY. always.
but this statement has a gotcha that most people don't fully get.
there are different "kinds" of drag and what helps or harms one will help or harm another.
the golf ball dimples HARM parasitic drag but IMPROVE base drag.
the improvement in base drag is "greater" than the hindering of parasitic drag so you see a "net gain"
frontal area and base drag have a far greater impact on fuel economy than "parasitic drag" or "SKIN" drag.
frontal area is when the air "slams into" something. Base drag is the "suck zone" behind your car.
these FAR outshadow parasitic drag.
this is why removing a mirror or atting a kammback or a grill block will see much larger "gains" than sealing up all the cracks in your body panels or "waxing" your car.
and could actually result in WORSE performance if you REDUCE parasitic drag because you also now make the "far worse" frontal/base drag worse.
the cleaner your frontal/base drag is the more important parasitic drag becomes.
so "clean lines" are far more important to an EV1 which has a very "clean" profile than it is for a "jeep cherokee" or pretty much any other normal car on the road.
this basically comes down to do the right thing at the right time.
Golf ball dimples on your hood will do nothing but make your drag worse.
but golf ball dimples on your kamback read half your roof and your rear quarter panels will IMPROVE performance. because why they increase your parasitic drag (lowering your fuel economy) they ALSO decrease your BASE DRAG by a far greater amount which improves your fuel economy by a lot more than the "decrease" from the worsening of parasitic drag.
and that is why the golf ball dimples work.
what would be interesting is "what size" is ideal ?
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