I'm about to buy a 96 S420 and I did not check if it had the double-thick glass.

 

Double-thick glass? Do you mean safety glass that has the film sandwiched between two sheets of glass? If so, yes. All cars do, except for original Model A's and Silver Ghosts and cars like those.

 

i think it's about the one with air gap inside which is more for heat absorbing and minimizing external noise than safety feature.

i can't be sure. my answer is 90% yes. the rest i need to find out.

 

Thanks!! I should have specified that I was asking about the door window glass. I would like to get a car with the double thick suff because it's so quiet.

 

My 96 S600 has double-glazing. It is very well insulated from outside noise.
Can't speak for all S models, but this is at least the same year that you are talking about.

 

The answer to your question is YES, S420 has the double-layered windows. All S-class W140s (92-99) have the double-layered glass with the inert gass in the middle to prevent the windows from fogging and dimming.

 

He is right. All S classes at least the W140 have that extra thick glass to

Insulation, Prevent fogging, and to have a more silent interior.

One step above that is offically bullet proof glass. Some S600 and 1995-1998 BMW 750ILs were made with that type of glass. Very thik and it was to add extra noise insulation and of course ballistic protection.

 

Correction, the bullet proof glass was just an extra bragging rights expensive option. Most common for those diplomats and politicans in Asia and Middle East and unsettled countries that really need that type of stuff. some of them went as far as rocket proofing the whole car. Off subject.

 

My 2000 S430 I just picked up today has double pane door glass. As I recall from the 92-99 the airgap seems thinner in the 2000.

 

it is