The Diplomat name was originally used by Dodge on 2door hardtop models from 1950 to 1954. It was also used on the export version of the DeSoto from 1946 through 1962. From 1975 through 1977, the Diplomat name was also used on a trim package available on the Royal Monaco twodoor hardtop. Starting with the 1977 model year, the Diplomat became a full model line, rather than as the name of a particular body style.

The second generation 1980 model year brought new exterior sheet metal for the Diplomat. The early '80s brought challenges to the auto industry, such as rising fuel prices and changing regulations. The Dodge Diplomat adapted to these times by offering a more fuelefficient six cylinder engine and a smaller V8, allowing it to remain relevant during an era of increased emphasis on fuel economy.

Interesting note, Chrysler's then executive vice president for manufacturing, Steve Sharf, met with officials at American Motors (AMC) to use the extra capacity at an assembly plant in Kenosha, Wisconsin to build the cars.[4]

About 250,000 Chrysler and Dodge models were built by AMC at a lower cost than Chrysler could. This relationship evolved into Chrysler's purchase of AMC in 1987.[4]

1981 was also the year that the police package version arrived. The Diplomat its sister the Plymouth Gran Fury were smaller than the Chevy and Ford competition, but had slightly better performance than the Ford and Chevy in certain years.

One of the reasons some police forces liked the Diplomat was that it was shorter than the Ford Crown Victoria and Chevrolet Caprice alternatives, making it more maneuverable in chases.
For 1985 a SE edition Diplomat went on sale with a restyled front end (looking like a Chrysler 5th Avenue) . A few SE edition Diplomats made their way into police forces, but these cars cost more. In the United States, the Dodge Diplomat outsold the Plymouth Gran Fury every year as cop cars.
The Dodge Diplomat's production came to a close in 1989, concluding an illustrious decadelong run.