What does the M mean in the Chrysler 300M?

The "M" simply signifies the next model in a series. In 1955 Chrysler introduced the C-300 (Chrysler-300 Horsepower). This series continued annually until the 300L in 1965. There was also the 300 Hurst in 1970. In 2005 Chrysler restarted the 300 letter series with an all new 300C.