Similar in concept to an automotive accessory receptacle, the DIN 4165 connector is shorter and smaller in diameter. It was originally a standard fitting on all the German military vehicles during World War II.
The DIN 4165 is also known as the BMW Accessory plug, as it is used on BMW motorcycles, the Powerlet connector, after of a firm that produces them, and, in Australia (where they are popular in mobile power applications, including 4WD and Caravaning), as the Hella plug, or Merit plug.
At least one manufacturer sells a plug that combines a cigarette lighter plug and a powerlet, in much the same way that combination auto/airplane notebook computer power adapters combine a cigarette lighter plug and an ARINC 628/EmPower plug.