Kei car is the smallest category of expressway-legal motor vehicles in Japan. Kei is short for ( ) 'light vehicle'.
With restricted dimensions and engine specifications, owners enjoy lower tax and insurance rates, leading to a lower overall ownership cost. In most rural areas, they are also exempt from the general Japanese parking-space ownership requirement to legally buy a motor vehicle at all, as street parking is generally restricted in Japan. Japan's carmakers also make microvans and kei trucks within this legal category. Kei cars are favored by both the elderly and younger demographics, including youths and young families, due to their affordability and ease of use.
The kei category was created by the Japanese government in 1949, to stimulate both car ownership and growth of Japan's car industry. The regulations were revised multiple times until 1998, but since October 1998, the law consistently specifies a maximum vehicle length of , width of , height under , and engine displacement under . A "gentleman's agreement" between Japanese automakers and lawmakers also set a maximum power output of .
Kei cars have been very successful in Japan since the 1960s, consisting of over one-third of domestic new-car sales in fiscal year 2016, after dropping from a record 40 percent market share in 2013. To reduce their market dominance, Japan increased taxes on the category by 50% in 2014. Despite this, in 2018, seven of the ten top-selling models were kei cars, including high-roof models with sliding doors such as the Honda N-Box, Suzuki Spacia, Nissan Dayz, and Daihatsu Tanto.
For exports, the vehicles are generally too small and specialized to be profitable. Notable exceptions exist; for instance, the Suzuki Alto and Daihatsu Cuore have been exported consistently since around 1980. The export version of the Suzuki Jimny, with upgrades to increase its width and power, has also gained significant popularity outside Japan.
Nearly all kei cars have been designed and manufactured in Japan, but some exceptions exist. A version of the European-built Smart Fortwo was briefly imported and officially classified as a kei car with modifications to reduce its width. In addition, the British Caterham 7 160 and the Polski Fiat 126p (after 1990) also received such classification.
Description
thumb|right|Private kei license plate
thumb|right|Commercial kei license plate
Japanese government regulations limit the outer physical size, and (combustion) engine displacement and power output of kei cars, see detailed table below. Kei cars have also been subject to other restrictions, chiefly lower speed limits than bigger vehicles; older Kei-cars also had a warning chime that sounded when being driven too fast.
Kei cars are issued special license plates, with black numbers on a yellow background for private use, and yellow numbers on a black background for commercial use, earning them the name "yellow-plate cars" in English-speaking circles.
Modern Kei cars are often available with turbocharged engines, automatic and continuously variable transmissions, and choice of front-wheel or all-wheel drive.
|-
! rowspan="2" style="text-align: left;" "width:9em" | Date
! rowspan="2" style="width:6em" | Max. length
! rowspan="2" style="width:6em" | Max. width
! rowspan="2" style="width:6em" | Max. height
! colspan="2" style="width:12em" | Max. displacement
! rowspan="2" style="width:12em" | Max. power<br><small>('gentleman's agreement between Japan's car- and lawmakers')</small>
|-
!| four-stroke
!| two-stroke
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| style="text-align: left;" | 8 July 1949
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| rowspan="7" |
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| rowspan="5"
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| style="text-align: left;" | 26 July 1950
| rowspan="3" |
| rowspan="3" |
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| style="text-align: left;" | 16 August 1951
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| style="text-align: left;" | 1 April 1955
| colspan="2" |
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| style="text-align: left;" | 1 January 1976
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| rowspan="2" |
| colspan="2" |
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| style="text-align: left;" | 1 January 1990
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| colspan="2" rowspan="2" |
| rowspan="2" |
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| style="text-align: left;" | 1 October 1998
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|}
History
Up to 360 cc era (1948–1975)
thumb|1958 [[Suzuki Suzulight SS]]
The kei legal class originated in the era following the end of World War II, when most Japanese citizens could not afford a full-sized car, though many had enough money to buy a light motorcycle. To stimulate growth of the car industry, as well as offer alternative commuting means, and small delivery vehicles for shops and businesses, the kei-car category, reduced tax-burden, and accompanying legal maximums for "essential transportation" vehicles were created. At first limited to a displacement of just 150 cc (or just 100 cc for two-stroke engines)<!-- conversion already in table above --> in 1949, dimensions and engine size limitations were gradually expanded in 1950, 1951, and 1955, to make kei cars more attractive to buyers, and production more viable to manufacturers.
In 1955, the displacement limit was increased to 360 cc for both two-stroke and four-stroke engines, resulting in several new kei car models beginning production in the following years. These included the 1955 Suzuki Suzulight and the 1958 Subaru 360 (considered the first truly mass-produced kei cars), which were 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 (MITI) 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 kei cars or the larger "national" cars. The small exterior dimensions and engine displacement reflected the driving environment in Japan, with speed limits in Japan realistically not exceeding in urban areas. Kei cars were not allowed to be driven any faster than 40 km/h until the mid-1960s, when the kei speed limit was increased to . The early vehicles were comparable to the European 'bubble-cars' of the era.
In 1968, with the introduction of the Honda N360, the domestic market for kei passenger cars began to grow rapidly. Before the model was launched on March 6, 1968, the monthly kei passenger car market consisted of less than 10,000 cars. This had swelled to 16,000 cars by March 1968 and over 18,000 by May. In May 1968, the 5570th N360 was registered, making it the market leader. Most kei cars registered were still in the commercial class, however.
The class then went through a period of ever increasing sophistication, with an automatic transmission appearing in the Honda N360 in August 1968, and front disc brakes becoming available on a number of sporting kei cars, beginning with the Honda Z GS of January 1971. Power outputs also kept climbing, reaching a peak with the Daihatsu Fellow Max SS of July 1970. Sales increased steadily, reaching a peak of 750,000 in 1970.
Until 31 December 1974, kei cars used smaller license plates than regular cars, at . From 1975, they received medium-sized standard plates, which are . To set them apart from regular passenger cars, the plates were now yellow and black rather than white and green.
550 cc era (1976–1990)
thumb|right|[[Daihatsu Hijet#Fourth generation (S38/S40)|Daihatsu Hijet (S40)]]
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 shrinking passenger kei car market in 1974 and 1976, respectively, although they both maintained a limited offering of commercial vehicles. Sales had been steadily declining, reaching a low of 150,000 passenger cars in 1975, 80% less than 1970 sales.
Emissions laws were another problem for the kei car industry in the mid-1970s. From 1973 to 1978, emissions standards were to be tightened in four steps. Meeting the stricter standards, which were to be introduced in 1975, would be problematic for manufacturers of kei cars. This was particularly hard for Daihatsu and Suzuki, which focused on two-stroke engines, and especially Suzuki, a relatively small company whose entire lineup consisted of two-stroke kei cars. Daihatsu, though, had both the engineering backing and powerful connections of their owner, Toyota, to aid them in meeting the new requirements. All manufacturers of kei cars were clamoring for increased engine displacement and vehicle size limits, claiming that the emissions standards could not be met with a functional 360-cc engine. In the end, the Japanese legislature relented, increasing the overall length and width restrictions by and , respectively. Engine size was increased to 550 cc,<!-- conversion already in table above --> taking effect from 1 January 1976.
Most manufacturers were somewhat surprised by the decision; having expected a 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. In 1980, another record year occurred as exports grew by 80.3% (to 94,301 units), of which 77.6% were microtrucks. Nearly 17% of exports went to Europe, dwarfed by Chile, which took nearly a quarter of the exported kei vehicles. This was also thanks to a new phenomenon: To help boost their sales, Suzuki developed a new car which could be sold as a commercial vehicle although it was really intended for private use, thus avoiding the 15.5% excise tax. Efficient, bare bones design meant that the resulting Suzuki Alto was considerably cheaper than any of its competitors, and it set the tone for kei cars for the entire 1980s. Until the excise tax was abolished in 1989, light commercials like the Alto and its competitors nearly completely supplanted the passenger car versions.
In the 1980s, the speed limit for kei cars was . Government rules also mandated a warning chime to alert the driver if this speed was exceeded.<!-- conversion already in table above -->
For the first time, a power limit of was also applied in addition to the limit on engine size, in response to the ever-increasing power outputs available with turbocharging and multivalve technologies popularized in the late 1980s. Engine technology was also shared with sports bikes, which are designed more for rider enjoyment and less so for fuel economy, going against the idea of small people's cars and putting the kei cars' tax and structural advantages at risk of a governmental backlash. This power limit matched the highest output reached by any kei manufacturer at the time and was a gentlemen's agreement amongst the manufacturers in an effort to avoid a kei-class horsepower war. The only kei car to have exceeded this limit is the Caterham 7 160, a lightweight British sports car that was not expected to qualify as a kei car, though it is small enough (in dimensions and displacement) to fit the regulations. Its engine is rated at —since that is how the car is homologated in the United Kingdom, Japanese authorities told the importer that its power should remain unchanged. The Japan Automobile Manufacturers Association also self-imposes a speed limit of for kei cars.
Kei cars were rather unsafe in accidents, and as a response, the Ministry of Transport decided to increase the standards. New kei cars would have to pass additional tests, including a head-on collision at and a side impact test. To enable manufacturers to fit additional reinforcements and crumple zones, the maximum overall length and widths were both increased by . The new rules went into effect on 1 October 1998 and all manufacturers introduced revised lineups to meet the new requirements. This was the largest, simultaneous introductions of new models in Japanese automotive history. The model was not a success, and sold the fewest examples of a kei car when it was marketed.
The process of consolidation in the kei class continued when, in 2008, Subaru announced that they would no longer develop and build their own kei vehicles. As Toyota had recently taken a stake in the company, Subaru was to sell rebadged Daihatsus instead to focus on their core vehicles and exports. The last true Subaru kei car left the band on the last day of February 2012, after 7.97 million examples had been built by the company over 54 years. Starting in 2011, Toyota entered the kei car market for the first time. The resulting Toyota Pixis Space, a rebadged Daihatsu Move Conte, which was expected to increase competition in that market. Nissan and Mitsubishi began to jointly produce the Mitsubishi eK (also sold as the Nissan Dayz and formerly the Nissan Otti). Honda's kei car lineup—the N-one, N-Box, and N-WGN—accounted for around a quarter of the company's overall sales.
Reduced incentives (2014–present)
thumb|[[Subaru Chiffon]]
In April 2014, the Japanese government significantly reduced advantages for kei car owners, imposing a higher sales tax, a higher gasoline tax, and a higher kei car tax, the last of which was raised by 50 percent—greatly reducing tax benefits compared to regular-sized cars. The i-MiEV uses a permanent-magnet synchronous motor powered by a 16 kWh lithium-ion battery pack. It can charge overnight in 14 hours from home 100-volt mains, or in 30 minutes from quick-charging stations installed at fleet locations. Its range is as tested by the US EPA, and as tested by the Japanese Transport Ministry. It was the world's first mass-produced electric car, and the first electric car to sell more than 10,000 units.
Rebadged and slightly updated variants of the i-MiEV were also sold in Europe as the Peugeot iOn and Citroën C-Zero. In 2011, Mitsubishi launched the MINICAB-MiEV; a battery electric version of the Minicab microvan, borrowing the drivetrain and key components from the i-MiEV. As of March 2015, over 50,000 units across all variants (including the two minicab versions sold in Japan) have been sold worldwide since 2009. Production of the i-MiEV was discontinued in 2021.
In May 2022, NMKV launched the Nissan-badged Sakura and the Mitsubishi-badged eK X EV in the Japanese domestic market. These models have a 20 kWh lithium-ion battery pack with an estimated WLTC range of . Both use a single electric motor with a maximum output of . The eK X EV is a battery-electric version of the Mitsubishi eK X, and the Sakura is an update to Nissan's Dayz line. The two are eligible for EV purchase incentives in Japan, and as of June 2022, are also the cheapest new BEVs from a major Japanese manufacturer.
In September 2025, Honda has started selling the N-One e: with an estimated WLTC range of .
In October 2025, BYD introduced the Racco, the first dedicated electric kei car from a non-Japanese maker.
Taxation and insurance
The vehicle excise tax levy is 2% of the purchase price, compared to 3% for a regular car. A 24-month insurance contract typically costs ¥18,980 at the time of registration versus ¥22,470 for a larger car.
An automobile weight tax also is levied: The amount is ¥13,200 and ¥8,800 for a three- and two-year period, respectively, as compared to the ¥18,900 and ¥12,600 charged for larger-sized 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. The required road tax is based on the engine's displacement.
Best-selling models
Gallery
;360 cc era
<gallery widths="200px" heights="150px">
File:Subaru360-1.jpg|Subaru 360<br />(1958–1970)
File:Mazda-r360-coupe01.jpg|Mazda R360<br />(1960–1969)
File:1972 Daihatsu Fellow Max Hardtop TL.jpg|Daihatsu Fellow<br />(1970–1976)
File:HondaN360.JPG|Honda N360<br />(1967–1972)
File:HondaLifeStepvan.JPG|Honda Life Step Van<br />(1972–1974)
File:Suzuki Fronte Coupe 001.JPG|Suzuki Fronte Coupé <br /> (1971–1976)
</gallery>
;550 cc era
<gallery widths="200px" heights="150px">
File:Daihatsu-Mira1st.JPG|Daihatsu Mira<br />(1980–2018)
File:Mitsubishi minica h21a lettuce 1 f.jpg|Mitsubishi Minica<br />(1962–2011)
File:1979 Suzuki Cervo CX-G.jpg|Suzuki Cervo (exported as the Suzuki SC100)<br />(1977–1982)
File:Subaru Sambar 401.JPG|Subaru Sambar<br />(1961–present)
</gallery>
;Kei sports cars
<gallery widths="200" heights="150">
File:MAZDA AZ-1.JPG|Autozam AZ-1 <br /> (1992–1994)
File:HondaBeat.JPG|Honda Beat <br /> (1991–1996)
File:SuzukiCappuccino.jpg|Suzuki Cappuccino <br /> (1991–1998)
File:1994 Subaru Vivio T-Top 660.jpg|Subaru Vivio T-top<br /> (1993–1994)
File:2015_Honda_S660.jpg|Honda S660 <br /> (2015–2022)
File:Daihatsu Copen 003.JPG|Daihatsu Copen <br /> (2002–2012, 2014–present)
File:2024 Caterham Seven 170S.jpg|Caterham 7 170
</gallery>
;Kei off-road cars
<gallery widths="200" heights="150">
File:Blue Suzuki Jimny XC (3BA-JB64W-JXCR-J) front.jpg|Suzuki Jimny <br /> (1970–present)
File:Mitsubishi PAJERO MINI Limited (ABA-H53A) front.jpg|Mitsubishi Pajero Mini <br /> (1994–2012)
File:Daihatsu Terios Kid.jpg|Daihatsu Terios Kid <br /> (1998–2012)
</gallery>
;Present
<gallery widths="200" heights="150">
File:Honda N-One (first) in Lunar Silver Metallic, front right.jpg|Honda N-One
File:Mitsubishi eK X space T 2WD (4AA-B35A-HXTTZ) front.jpg|Mitsubishi eK X space
File:Suzuki WagonR HYBRID FX MH55S.jpg|Suzuki Wagon R
File:2019 Nissan Dayz X.jpg|Nissan Dayz
File:Mazda CAROL GX (DBA-HB36S) front.jpg|Mazda Carol
File:Toyota PIXIS JOY F G Turbo"SA II" (DBA-LA250A-GBVZ) front.jpg|Toyota Pixis Joy
</gallery>
See also
- Kei truck