The cars feature yellow license plates, earning them the name "yellow-plate cars" (black numbers on yellow background for private use and yellow numbers on black background for commercial use) in English-speaking circles. Because regulations only restrict physical size and engine displacement (and latterly outright power), manufacturers have been able to introduce many advanced technologies to the class. As a result, kei cars are often available with forced-induction engines, automatic and CV transmissions, front-, rear-, and four-wheel drive, air conditioning, GPS, and many other features.
Daihatsu, Honda, Mitsubishi, and Suzuki all manufacture kei cars, while Nissan sells badge-engineered Mitsubishi and Suzuki models, Mazda offers badge-engineered Suzuki models, and Toyota and Subaru offer badge-engineered Daihatsu models. German brand Smart offered a kei version of its Fortwo called the Smart K in Japan at Yanase dealerships from 2001 to 2004 with specially developed rear fenders, reduced tire dimensions and track width, to conform to kei car standards, though ultimately the model sold the fewest examples of a kei car when it was marketed.