The Mitsubishi Debonair is a four-door luxury car, introduced by Mitsubishi Motors in 1964 to serve as their flagship passenger vehicle in the Japanese domestic market. Three distinct generations were available during its 35-year production run until it was discontinued in 1999. The first and second generation models were used by senior level executives of the Mitsubishi Group and affiliated companies, or essentially a Mitsubishi senior executive company car made by the motor vehicle division of Mitsubishi.
The Debonair was Mitsubishi's competitor to the Nissan Cedric and Toyota Crown and during the first generations production, the appearance remained generally unchanged from 1964 - 1986, sharing an appearance tradition with the Toyota Century, that being iconically recognized as a senior executive sedan. Although it received several minor redesigns (denoted I through IV in Roman numerals), the vehicle proved popular enough in the Japanese executive market to remain in production for 22 years without major appearance modifications. The market introduction of the Honda Legend in 1986 influenced many traditional Japanese models to update the appearance of their vehicles, including the Debonair.
Powered by the KE64 1991 cc straight-6 engine with twin carburettors and dual exhausts, it developed 105 PS (77 kW; 104 hp) at 5,000 rpm, and had a maximum speed of 155 kilometres per hour (96 mph). During the 1970s, the Saturn 6 1994 cc straight-6 engine was adopted, boosting power to 132 PS (97 kW; 130 hp) and giving the car a top speed of 180 kilometres per hour (112 mph). Models from the later 1970s onwards were powered by Mitsubishi's Astron 2.6L 4-cylinder engine.
The Debonair was briefly offered in Europe during the 1960s, but demand reduced after Fiat introduced the Fiat 2300.
In 1986 the Debonair adopted a front-wheel drive format, a cost effective way to increase interior space without investing money on engineering in an executive sedan. It also came with Mitsubishi's first V6 engines, the 6G71 2.0 L and the 6G72 3.0 L. A supercharged version of the smaller engine was added to the line-up in 1987, using the world's first needle roller rocker arm assembly. This generation, and its successor, were also sold as the Hyundai Grandeur.