Noun
kei car (plural kei cars)
A Mitsubishi Pajero Mini, an example of a kei car
A classification of light passenger automobiles sold in Japan. Vehicles of this type are distinguished by the use of smaller engines (with displacement up to 660 cc), and yellow and black (or black and yellow) license plates.
In Japan, they are regulated under the Kei car laws, which allow vehicle owners a break in taxes for buying a smaller and less-powerful vehicle (currently, the engine is limited to 660 cc displacement). Source: Internet