[Tesla]

After reading some threads where both maintaining lower speeds and aero mods were discussed, I began to think these two are mutually exclusive.
Aero mods are only effective at higher speeds and one would even question if increased skin drag at lower speed would result in negative impacts.

I may be wrong but as I understand it below about 45mph the only real relevance aero has is in cross sectional area, and outside cutting the roof off it other aero mods do not change this factor. so boat tails, side skirts and even grill blocks are probably a waste of time if you spend most of your time at lower speeds.

Aero drag is primarily the simple power:velocity relationship, which basically says double speed and power required is increased 8 fold, hence power required at 45mph is less than half of that at 60mph just to push the air out of the way.

Then there is the speed and form relationship, the greater the speed the greater the turbulence, as I understand it form becomes less relevant at lower speeds, boundary layer becomes thinner, turbulence is reduced, so the only thing you get by the nose cone, boattail, wheel covers etc is lots of strange looks.

I think many people overlook this, if it is purely a town car, then Hypermiling is the way to go, if you do a lot of HWY at speed, then get some aero on as well.