I have them, and it did help reduce the cabin wind noise when the windows are down.
I've been running these Weathertech visors on my other vehicle for years now, and decided they are a must have for the Volt. In this area the summer heat (which has already started) is unbearable so many folks roll their windows down slightly to allow a little ventilation in the cabin. Unfortunately, this area is also known for its scattered showers that seem to pop up without notice. So with these visors, I can keep the windows down an inch or so to allow the heat to escape from the interior without worrying about rainwater ruining the leather seats. Took me about 10 minutes to install, and they fit tight and secure in the window frame. After running the windows up and down a couple of times, they seated properly and made themselves right at home. I got the light tint visors, they are also available in a darker tint. These are top quality and well worth the price.