There are 2 design cues in the prototype that unfortunately appear to be somewhat lost on the mules. A more aggressive rear wing and a raised hump over the rear wheel. Both, if my eyes don't deceive me, are greatly reduced or eliminated on the mules (the wing is smaller and the hump is gone, replaced by a straight line). And if so, I would bet heavily they were both due to aerodynamics. Regardless, I think people will be pleased when real production models are shown. Musk cares about both style and function, and the X will likely be the best possible compromise of both. If you fail on style, you end up with a functional car that looks like a turd. If you fail on function, you end up with a Fisker. I believe the X will succeed on both as best it can.