Wow! People actually buy that? I really must dig into my box of random crap and see what I can sell.
@e-yes yup it's a thing, but like the thread you have linked there it's a 1-3dB difference. Most of the heavy lifting is done by the structural sound proofing. Was in an electric (no range extender engine) BMW i3 the other day, ignoring the terrible ride quality, it was loud compared to the ES in town.
Since we're talking quiet cabins here. It can be quiet enough in the ES that I can hear faint wind noise coming from the sunroof area at motorway speeds. Just closing the blind is enough to make it go away. Anyone else here noticed that? Yes I checked the seals while open and closed, it opens and closes normally, and when closed I don't feel any air movement on the inside at speed. I checked the outside parked, seems to be a snug fit, nothing popping over or in fact under the roof/bodywork. Now I'm obviously being nitpicky here, just curious if anyone else noticed it.