This was a reality in WW2.

T17E1: Built by Chevrolet for Britain. An order for 2,000 was placed in January 1942. First vehicles were produced in October 1942. 157 were finished by January 1943. Originally was to be used by US Army but order was canceled after Special Armored Vehicle Board decided that US didn't need armored cars in this weight and size. British like it and all production was sent to Britain.