akohekohe wrote:For whatever reason the Dealer put this bracket on the undercarriage to hold the inspection stickers. There is no reason to do this except some people don't like the stickers attached to the rear bumper (which is where they are usually put). I think this the bracket messes with the aerodynamics but maybe I don't know what I'm talking about. What do you think?
First, please resize your image to a maximum width of about 800 pixels. That will make it a lot easier to see.
To answer your question, any external change to the body will affect the aerodynamics, even a front license plate will do so. The real question is: How much?
I don't think this will affect it any noticeable amount given the other things that affect mileage (wind, driving style, etc) and I wouldn't worry about it. Personally, the sticker has to be there one way or another... I would wonder if it could be moved to the rear window (like in a corner), that way your paint job/bumper isn't affected and isn't on a plate possibly affecting the natural aerodynamics of the car.