Hanging armored plate on vehicles became a popular pastime since cars were built, especially when people wanted to shoot at you.  The Kubus was designed on the fly and built in 13 days just in time for the Warsaw Uprising in August 1944.  The design was credited to Walerian Bielecki by Wikipedia, and another worker, Jozef Fernik, contributed the name, which was the nickname of his wife recently killed by the Germans.  The Poles gathered together all the steel plates they could cobble together and shot at them to gauge their usefulness. The thinner ones seemed to do better at angles, and their best plates came from bank safes.  All this was hung on a 1938 Chevrolet truck, license built by the Poles locally, and modified to run on wood gas, as real gas was impossible to get.  The resulting vehicle could carry 12, sported a Soviet 30 caliber machine gun and a homemade flamethrower.  

The Kubus armored car 

The Kubus took part in several attacks on the University of Warsaw.  It's combat career lasted  just nine days, less than it took to build.  The Germans holed up at the University had no heavy or armor piercing weapons, however the Poles were unable to drive them out and finally had to abandon Warsaw entirely.  The Kubus was abandoned and unbelievably survived the war, and is on display at the Warsaw Uprising Museum.  A replica has also been built.