right|thumb|250px|[[스바루 R1]]
'''경자동차'''(, , K-car)는 660씨씨 이하의 배기량를 가진 소형 자동차로 일본에서 사용되는 자동차 종류의 하나이다. 대한민국에서의 경차와 마찬가지로 각종 세제혜택으로 인해 일본에서의 인기가 높다.

경자동차의 역사는 제2차 세계 대전이 끝난 시기까지 거슬러 올라간다. 당시 일본인들은 전쟁으로 인해 오토바이 구매력은 있었으나, 대형차를 구매할 수 있는 사람은 매우 적었다. 당시의 자동차 산업을 육성하고 자영업자들의 저렴한 운송 수단을 지원하기 위해 정부차원에서 경자동차 규격이 제정되었다.

경자동차 규격은 크기와 엔진 마력수에 제한을 두기 때문에, 자동차 제조사들은 수많은 신기술을 집약하는데 집중해 왔다.

==규격의 변천==
{| class="wikitable" style="text-align:center; padding:5px;"
|-
! rowspan="2" style="width:9em" | 시행일시
! rowspan="2" style="width:6em" | 전장
! rowspan="2" style="width:6em" | 전폭
! rowspan="2" style="width:6em" | 전고
! colspan="2" style="width:12em" | 최대엔진배기량
! rowspan="2" style="width:6em" | 최대마력수
|-
!| 4행정 기관
!| 2행정 기관
|-
|| 1949년 7월 8일 
|| 2.8 미터
|| 1 미터
| rowspan="7" | 2 미터
|| 150 씨씨
|| 100 씨씨
| rowspan="5" | 해당사항없음
|-
|| 1950년 7월 26일 
| rowspan="3" | 3 미터
| rowspan="3" | 1.3 미터
|| 300 씨씨
|| 200 씨씨
|-
|| 1951년 8월 16일 
|| 360 씨씨
|| 240 씨씨
|-
|| 1955년 4월 4일 
| colspan="2" | 360 씨씨
|-
|| 1976년 1월 1일 
|| 3.2 미터
| rowspan="2" | 1.4 미터
| colspan="2" | 550 씨씨
|-
|| 1990년 3월
|| 3.3 미터
| colspan="2" rowspan="2" | 660 씨씨
| rowspan="2" | 64 마력 (47 킬로와트)
|-
|| 1998년 10월 1일 
|| 3.4 미터
|| 1.48 미터
|}

thumb|right|The [[Daihatsu Cuore, a popular and typical ''kei car''.]]
 (pronounced /keːdʑidoːɕa/), is a Japanese category of small passenger cars, JAMA, January-February 2005</ref><ref name="sendai">

[http://www.sendaiedu.com/owningacar.html "Owning a Car in Japan"], ALTs in Sendai</ref> 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.

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.<ref name="sendai"/><ref name="yellow1">[http://www.jetsetjapan.com/infozone-trans-auto.shtml Automobiles], jetsetjapan.com</ref><ref name="yellow2">[http://www.city.obihiro.hokkaido.jp/hp/data/page000004200/hpg000004177.htm "Shakoshomei 車庫証明(proof that you have a place to park your car)"], ''Driving in Tokachi'', city.obihiro.hokkaido.jp</ref>
Because the regulations only restrict physical size, engine displacement and power, manufacturers have introduced many advanced technologies to the class. As a result, kei cars are often available with automatic and CVT transmissions, front-, rear- and hybrid drivetrains, air conditioning, GPS and many other features.

Historical reasons aside, kei cars of today are generally quite fuel efficient due to their small displacement <660cc engines, and are valued commuter cars in Japan due to high gasoline prices exacerbated by steep gasoline taxes.  The small size requirements of the cars is also a consideration in narrow streets and tight parking spaces in Tokyo, where nearly a third of Japan's population resides.

Mitsubishi, Smart,<ref name="nytimes">[http://www.nytimes.com/2007/11/25/automobiles/25MICRO.html?ref=automobiles "Small Things in Good Packages"], Jerry Garrett, ''New York Times'', November 25 2007</ref> Subaru, and Suzuki all manufacture kei cars. Nissan sells Mitsubishi and Suzuki models while Mazda sells Suzuki models under licence badge engineering.<ref name="oem">[http://www.edmunds.com/insideline/do/News/articleId=106031 "Nissan Adds Third Minicar to its Lineup in Japan"], Edmunds.com, June 6 2005</ref>

Wagon R has captured the top slot for the fifth straight year.
The Wagon R was the best-selling keicar in Japan in the first six months of 2008. Including the Wagon R, six of the 10 best-selling models in Japan were keicar, an indication that fuel-efficient automobiles continued to be popular on the back of soaring fuel prices. [http://www.sgcarmart.com/news/article.php?AID=1346]

==History of regulations==
{| class="wikitable" style="text-align:center; padding:5px;"
|-
! rowspan="2" style="width:9em" | Date
! rowspan="2" style="width:6em" | Maximum length
! rowspan="2" style="width:6em" | Maximum width
! rowspan="2" style="width:6em" | Maximum height
! colspan="2" style="width:12em" | Maximum displacement
! rowspan="2" style="width:6em" | Maximum power
|-
!| four-stroke
!| two-stroke
|-
|| 8 July 1949
|| 2.8 m
|| 1 m
| rowspan="7" | 2 m
|| 150 cc
|| 100 cc
| rowspan="5" | n/a
|-
|| 26 July 1950
| rowspan="3" | 3 m
| rowspan="3" | 1.3 m
|| 300 cc
|| 200 cc
|-
|| 16 August 1951
|| 360 cc
|| 240 cc
|-
|| 4 April 1955
| colspan="2" | 360 cc
|-
|| 1 January 1976
|| 3.2 m
| rowspan="2" | 1.4 m
| colspan="2" | 550 cc
|-
|| March, 1990
|| 3.3 m
| colspan="2" rowspan="2" | 660 cc
| rowspan="2" | 47&nbsp;kW (64&nbsp;PS) (63 hp)
|-
|| 1 October 1998
|| 3.4 m
|| 1.48 m
|}