Are you sure about that? I'm not. The Zils have been in the Russian fleet for a long, long time. I think that is a testament to their construction. American security limousines do not last ten-years in the government fleet.

As far as I know, Zils have a different design and build than factory-produced armored cars. Zils also have full B7-level armor. Even the glass, which is over two-inches thick, is rated B7. That ought to be a higher protection than any S-Class Guard, in my opinion. S-Class Guards are B6/B7 so I reckon their glass is not as strong as an armored Zil's glass.