Well, I guess its all on aero mods then.
- boat tail
- cheap pizza pan wheel covers (expensive moon caps don't really pay back)
- rear wheel skirts (another few %)
- "wheel spats" or small boattails behind the wheel. (Doesn't the prius have those already though?)
- antenna delete or replace with sharkfin
- right side mirror delete (if legal?)
- replace side mirrors with more aerodynamic ones / smaller ones, if possible. add wideview internal mirror for safety.
- get the grill block back in, and with a moveable opening. Bowden cable for control seems like an excellent idea.
(Perhaps car manifacturers will add thermostat controlled grill louvres in the future. open when its hot, closed when its not.
)
- Perhaps using some rubber strip material to fill in the gap between the body and the front wheels, but in such a way that it wouldn't rub in corners and over bumps. (easier and nicer-looking than hinging front wheel skirts.
- Belly pan (if not already fitted)
- Air dam (depending on how much stuff is under the car)