My opinion --- Negligible drag especially when mostly driving at 30 to 50MPH in town.
Also, removing a side mirror might just be a legal problem if in an accident (modifying OEM), and could result in an accident.
Side mirrors have a purpose IMO.
Absolutely, good aerodynamics have a much smaller effect at those speeds. Most of my miles are cross country and every little bit makes a difference.
You cannot be found at fault for removing safety equipment that is not the proximate cause of the accident. In this case, the only possibility of an accident is a right lane change blind spot - rather rare in the absence of alcohol - I don't drink. I've not had one ever in many hundreds of thousands of miles and 45 years driving and have never observed one.
I substitute a much larger windshield mirror with a slight curvature that gives me a panoramic view of all my right side windows and the rear window. The blind spot is actually less than with an OEM side mirror.
Things will be better when NHTSA allows video cameras to replace side mirrors. Far better visibility and far better aerodynamics.
Well, what model did you end up buying? If you got anything other than the FE, you're giving up one or two, to several MPG's. Also the roof rack, or even the side rails are drag. The standard transmission instead of CVT, and the raised height was a compromise, so you could buy a more efficient make instead(Prius). I guess you could remove the floor mats and glove compartment door, back seats if not used, as well as all cups/bottles/coins. That is unneeded weight that lowers fuel economy. That would seem to make more sense than removing a possible safety item.
My EX (with tech package) has chrome seams around the windows so the stick on type will not work as the visors will cover up PART of the chrome trim. Will have to wait for WeatherTech's in-channel window visors to come out later....I hope.
I never used them on any of my cars until I bought a Dodge Dakota pickup that had them installed already. It took about 3 days to figure out how good they are! Now I put them on all my cars. Yup....they look pretty old fashioned but they have a lot of advantages.
The main one for me is when I'm driving and the sun is to the side of the car, which happens for me 90% of the time, there is no glare at all in my eyes. It's like sunglasses for the side windows.
Plus run with the window open a crack for fresh air, even when it's raining (might even improve aerodynamics in that state...air doesn't rush in with the window open)
Plus reduces wind noise with the wind open a crack.
And if they make my car look ugly, it's less likely to get stolen!! Plus.