I'm all for trying something outside-the-box.



But I think you may be overestimating the effect of the double windows alone. By 1998 noise control had touched most aspects of car design, particularly on a Benz like that. The aero of the body. Resonance frequencies cause by the steel shapes of the parts. They used heavy sound deadening under EVERYTHING. The heat/AC system is designed to operate more quietly. They were starting to use two layers of rubber weatherstripping seals for the door opening. Etc.


As for the cooler temps, I agree with the suggestion to tint the glass with good modern ceramic film. It blocks certain wavelengths better than older tints. You can get the cooling effect of a dark tint but it looks like a lighter shade to the human eye.