Kei car, K-car, or keijidōsha (軽自動車, lit. "light automobile") (pronounced [keːdʑidoːɕa]), is a Japanese category of small vehicles, including passenger cars, vans, and pickup trucks. They are designed to comply with Japanese government tax and insurance regulations, and in most rural areas are exempted from the requirement to certify that adequate parking is available for the vehicle. This especially advantaged class of cars was developed to promote popular motorization in the post-war era. While successful in Japan, the genre is generally too specialized and too small to be profitable in export markets.
The cars feature yellow licence 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- and Spanish-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 CVT transmissions, front-, rear- and four-wheel drive, hybrid drivetrains, 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 offers 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, however it suffered from poor sales and was the worst-selling kei car of its time.
360 cc era 
These standards originated in the times following the end of the Second World War, when most Japanese could not afford a full-sized car yet had enough to buy a motorcycle. To promote the growth of the car industry, as well as to offer an alternative delivery method to small business and shop owners, kei car standards were created. Originally limited to a mere 150 cc (100 cc for two-strokes) in 1949, dimensions and engine size limitations were gradually increased (in 1950, 1951, and 1955) to tempt more manufacturers to produce kei cars. It wasn't until the 1955 change to 360 cc as the upper limit for two-strokes as well as four-strokes that the class really began taking off, with cars from Suzuki (Suzulight) and then Subaru 360 finally able to fill people's need for basic transportation without being too severely compromised. In 1955, the Japanese Ministry of International Trade and Industry also set forth goals to develop a "national car" that was larger than kei cars produced at the time. This goal influenced Japanese automobile manufacturers to determine how best to focus their product development efforts for the smaller kei cars, or the larger "national car".
The class then went through a period of ever increasing sophistication, with an automatic transmission appearing in the Honda N360 in August 1968, with front disc brakes becoming available on a number of sporting kei cars, beginning with the Honda Z GS of January 1970. Power outputs also kept climbing, reaching a peak in the 40 PS (29 kW; 39 hp) Daihatsu Fellow Max SS of July 1970. Sales increased steadily, reaching a peak of 750,000 in 1970. Throughout the 1970s the government kept whittling away at the benefits offered to kei vehicles, which combined with ever stricter emissions standards to lower sales drastically through the first half of the decade. Honda and Mazda withdrew from the contracting passenger kei car market, in 1974 and 1976 respectively, although they both maintained a limited offering of commercial vehicles.
Until 31 December 1974, Kei cars used smaller license plates than regular cars (230 x 125 mm). As of 1975, Kei cars received the medium sized standard plates (330 x 165 mm). To set them apart from regular-sized cars (non-kei), the plates were now yellow and black rather than white and green.
550 cc era 
Sales had been steadily declining, reaching a low water mark of 150,000 passenger kei cars in 1975, eighty percent less than 1970 sales. Many were beginning to doubt the continued existence of the Kei car, with both Honda and Mazda withdrawing in the middle of the seventies.
The even stricter emissions standards which were to be introduced in 1975 as part of a staggered program of cleaning the air proved problematic for kei manufacturers.[n 1] This was particularly hard for Daihatsu and Suzuki who focused on two-stroke engines. Tiny Suzuki was worst off, with their entire production consisting of two-stroke engined kei cars. Daihatsu, on the other hand, had both the engineering backing and powerful connections of their large owner Toyota to aid them in meeting the new requirements. All manufacturers of kei cars were clamoring for relaxing the dimension conditions, claiming that the emissions standards could not be met with a functional 360 cc engine (even though Subaru's SEEC-T equipped Rex proved it possible). In the end, the Japanese legislature relented, increasing the overall length and width restrictions by 200 mm and 100 mm respectively. Engine size was increased to 550 cc, taking effect from January 1, 1976.
Most manufacturers were somewhat surprised by the decision: having expected a 500 cc limit, they had already developed new engines to fit such restrictions. These new engines were quickly introduced, usually mounted within widened bodies of existing models. These interim versions (with displacements ranging between 443 and 490 cc) were "feelers", developed to see if there was indeed a continued market for the Kei car. As sales improved, they only lasted for a model year or so until manufacturers had had the time to develop "full-size" engines. Only Daihatsu managed to avoid developing transitional engine versions which did not take full advantage of the new regulations. Kei car sales remained stagnant however; while combined passenger and commercial Kei car sales reached 700,000 for the first time since 1974, in a quickly growing market the small cars still lost market share.
660 cc era 
In March 1990, new standards were again introduced. An extra 110 cc were now allowed in a slightly larger (10 cm longer) bodyshell. These changes came at a time when the Japanese economy was booming, so all manufacturers quickly developed new models to suit. The only 550 cc model to continue to be available for a while was the Mitsubishi Minica Dangan, which was only upsized five months later. As a response to ever increasing power, a limit of 64 PS (47 kW; 63 hp) was also added. 64 PS happened to be the highest outputs to have been reached at the time, it is unknown if there are any other reasons that this number was selected. The regulation of horsepower has been suggested due to the fittment of turbochargers and superchargers to these tiny engines during the late 1980s in order to cope with the lack of horsepower and torque, and the installation of turbos and superchargers made the vehicles very fast and nimble relative to their size. Engine technology is also shared with Sport bikes, which are designed for rider enjoyment, and less so on fuel economy.
History of regulations 
|Date||Maximum length||Maximum width||Maximum height||Maximum displacement||Maximum power|
|8 July 1949||2.8 m (9.2 ft)||1 m (3.3 ft)||2 m (6.6 ft)||150 cc||100 cc||n/a|
|26 July 1950||3 m (9.8 ft)||1.3 m (4.3 ft)||300 cc||200 cc|
|16 August 1951||360 cc||240 cc|
|4 April 1955||360 cc|
|1 January 1976||3.2 m (10.5 ft)||1.4 m (4.6 ft)||550 cc|
|March, 1990||3.3 m (10.8 ft)||660 cc||47 kW (64 PS; 63 hp)|
|1 October 1998||3.4 m (11.2 ft)||1.48 m (4.9 ft)|
Present day 
Starting in 2011 Toyota Motor Corp launched its first minicar the Pixis Space which is expected to increase competition in the minicar sector. Currently Nissan Motors is in partnership with Mitsubishi Motors who produces the minicars for Nissan, while Honda's minicar sales total around a quarter of its overall sales.
Financial advantages 
- Vehicle excise tax
- Taxable amount is only 3% of the purchase price, compared to 5% for a larger car.
- Automobile weight tax
- The amount is 13,200 and 8,800 yen for a three and two year period respectively; as compared to the 18,900 and 12,600 yen charged for larger size passenger cars. The savings are thus more than 30% in both cases. This weight tax is paid after the vehicle has passed its safety inspection.
- Automobile liability insurance (compulsory insurance) premiums
- A 24-month insurance contract typically costs 18,980 yen at the time of registration, versus 22,470 yen for a larger car.
- Annual road tax, which is based on the engine's displacement size
Financial disadvantages 
Due to the popularity of "light cars", there is a tax on the size of these vehicles called the Light Motor Vehicle Tax. The amount charged for the size of "Passenger Cars" (the largest of the three classifications recognized in Japan) is 7,200 yen (US$83.50), or 4,000 yen ($46.40) for commercial vehicles. Normally the car tax on "light cars" below 1,000 cc is 29,500 yen ($342), with passenger cars and trucks with a load carrying capacity of 1,000 kg or less is at 13,200 yen ($153). (Some local governments may charge even higher based on local regulations).
After World War II, Kei car was born as the public car. The engineers of the erstwhile Nakajima Aircraft Company developed the first truly successful Kei car, the Subaru 360.
The Kei sports car was born by "Bubble boom" in the latter years of the 1980s, although a few sporty iterations such as the Fronte Coupé, Honda Z and Minica Skipper had appeared in the early seventies.
Honda Beat (1991-1996)
Suzuki Cappuccino (1991-1998)
Autozam AZ-1 (1993–1995)
Daihatsu Copen (2002-2012)
The engine capacity has been expanded to 660 cc (in 1990) to aid high-speed performance and the increased weight of new safety equipment. Ever tighter safety regulations have also necessitated a slightly larger body, since 1998. Most of the vehicles sold currently are built as what is called a "tall boy" or "tall wagon" appearance, using four doors, a one piece hatchback, and expanded head room.
Commercial vehicle 
- Beginning in 1973, the emissions standards were to be tightened in four steps. Interim emissions standards were introduced in 1975 and 1976, with the ultimate installment arriving in 1978.
- Nunn, Peter (January–February 2005). "Minicars: Cheap and Cheerful". JAMA. Retrieved 2012-05-10.
- "Owning a Car in Japan", ALTs in Sendai
- "Small Things in Good Packages", Jerry Garrett, New York Times, November 25, 2007
- Rees, p. 79 Microcar
- "Nissan Adds Third Minicar to its Lineup in Japan", Edmunds.com, June 6, 2005
- "THE 37th TOKYO MOTOR SHOW". Japan Automobile Manufactures Association. Retrieved 11 November 2011.
- Rees, p. 78 Microcar
- Nippon Kei Car Memorial, p. 79 Nippon
- Nippon Kei Car Memorial, p. 75 Nippon
- Yamaguchi, Jack K. (1977), "The Year of the Third Power", World Cars 1977 (Pelham, NY: The Automobile Club of Italy/Herald Books): 56, ISBN 0-910714-09-6
- Yamaguchi, Jack K. (1979), "The Year of Uncertainty?", in Lösch, Annamaria, World Cars 1979 (Pelham, NY: The Automobile Club of Italy/Herald Books): 61, ISBN 0-910714-11-8
- Yamaguchi, Jack K. (1976), "Japan: Reluctant Number One", World Cars 1976 (Bronxville, NY: L'Editrice dell'Automobile LEA/Herald Books): 56, ISBN 0-910714-08-8
- "Goo-net カタログ: 三菱 ミニカ(MINICA)のグレード一覧: 1990年8月" [Goo-net Catalog: Mitsubishi Minica, 1990.08] (in Japanese). Goo-net. Retrieved 2011-10-21.
- "Toyota adds first minicar to Japan lineup". japantoday.com. Japan Today. Retrieved 27 September 2011.
^ 360cc: Nippon 軽自動車 Memorial 1950→1975 [Nippon Kei Car Memorial 1950-1975] (in Japanese). Tokyo: Yaesu Publishing. 2007. ISBN 978-4-86144-083-0.
^ Rees, Chris (1995). Microcar Mania. Minster Lovell & New Yatt, Oxfordshire, UK: Bookmarque Publishing. ISBN 1-870519-18-3.
|Wikimedia Commons has media related to: Kei cars|
- History of regulations
- (subscription required) The minicar and the emerging markets, Andrew Mollet, Automotive World, March 1, 2003
- (Japanese) 全国軽自動車協会連合会