H/T Atlas Obscura.
There was a story about how this car was used to protect President Franklin D.Roosevelt after the bombing of Pearl Harbor on December 7,1941 it is totally false.
The truth is at this link.
It featured bullet-proof glass and a police siren.
In the world of organized crime, Al Capone had few equals. For seven years in the 1920s, as the boss of the Chicago Mafia during Prohibition, Capone shocked the city with bombings, heists, gambling, prostitution, and other sundry criminal activities.
One of his greatest methods of escaping was via a “killer” car—an armored, bullet-proof vehicle weighing over three-and-a-half-tons, and capable of speeding off at 110 mph. In the 1933 film above, archived by British Pathé, a small group gathers as a man shows the many inconspicuous features of Capone’s car that enabled him a quick get-away in dicey situations.
The 1928 Cadillac Model 341A Town Sedan was equipped with a regulation police siren to fool other drivers. It also had bullet-proof glass installed throughout, causing the doors to weigh a hefty 10 stone (or approximately 140 pounds). The thick glass even required special springs and gears to raise and lower the windows. In order to see if the coast was clear, Capone could also snoop in on police activity with the “first regulation police pick-up radio” that had ever been installed on an automobile.