Why kei cars were 36.5% of Japan's new vehicle market in 2025, the regulatory class no other country has

What is a kei car? A kei car (keijidosha, "light vehicle") is a Japanese vehicle class with legal limits on size and engine: at most 660cc displacement, 3.40m long, 1.48m wide and 2.00m tall. Those limits have applied since 1 October 1998 (Zenkeijikyo, kei car standards). The current standard is written in displacement and dimensions only; it sets no legal power figure. Staying inside the limits buys lower annual tax and, in many areas, no proof-of-parking requirement, which is why kei cars are about a third of Japan's market.

2026 so far: from January to September 2026 Japan sold 1,262,765 kei vehicles out of 3,545,421 new vehicles in total, a 35.6% share (JADA registered vehicles 2,282,656 plus Zenkeijikyo kei 1,262,765; JADA, 1 October 2026; Zenkeijikyo, 1 October 2026). Counting passenger cars only, 973,862 kei passenger cars against 1,987,368 registered passenger cars gives kei 32.9% of 2,961,230. September alone: 433,683 vehicles, of which 161,783 kei (Japan September 2026). Monthly totals are on the Japan dashboard.

Kei cars, Japan's regulated micro-vehicle class with a 660cc engine cap and strict size limits, were 1,667,360 of the 4,565,777 new vehicles sold in Japan in 2025, a 36.5% share, up 7.0% on 2024 (JADA and Zenkeijikyo via Nippon.com, 20 January 2026). Counting passenger cars only, 1,302,857 kei passenger cars against 2,533,523 registered passenger cars gives kei a 34.0% share, about one new car in three. The Honda N-Box sold 201,354 units, the best-selling nameplate in Japan across both classes.

Top Japanese nameplates 2025, kei vs registered

Nameplate	Class	2025 units
Honda N-Box	Kei	201,354
Toyota Yaris	Registered	166,533
Suzuki Spacia	Kei	165,589
Toyota Corolla	Registered	138,829
Daihatsu Tanto	Kei	124,619
Toyota Sienta	Registered	106,558

Source: JADA and Zenkeijikyo nameplate rankings for January to December 2025, published 8 January 2026 (Car Watch). The top three of each class are shown.

Why kei cars exist

Three regulatory advantages make kei cars cheaper to own than any registered passenger vehicle:

1. Annual road tax. The standard kei vehicle tax for a private four-wheel kei passenger car registered from April 2015 is ¥10,800 a year (Sagamihara City, kei vehicle tax rates), well below the engine-size-based automobile tax on registered cars.
2. Parking proof. In many areas kei cars do not need the shako shoumeisho, the proof-of-parking-space certificate required for registered cars, which removes a real barrier to ownership.
3. Running costs. Smaller engines and lighter bodies keep fuel and other running costs down, which matters most to buyers who use a car for short local trips.

The kei BEV story

The Nissan Sakura and Mitsubishi eK X EV (twins built on the same NMKV platform) launched in mid-2022. The kei size limits suit a small battery, which keeps the price of these cars down, and the Nissan and Mitsubishi joint venture shares the engineering between the two brands.

Why no other country copies the kei format

The kei class only works because Japan combines four conditions: dense urban infrastructure that punishes large vehicles, a cooperative regulator that ring-fences a tax bracket for tiny cars, a domestic OEM ecosystem (Honda, Suzuki, Daihatsu, Mitsubishi) prepared to compete in low-margin segments, and a cultural willingness to drive small. India has the urban density, China has the OEM ecosystem, but neither has the regulatory framework that turns "small" into a structural cost advantage.

Source & methodology

Sales figures from JADA (Japan Automobile Dealers Association) for registered cars and JAIA (Japan Automobile Importers Association) for imports. Kei sales are pulled from the parallel Zenkeijikyo federation (Japan Light Motor Vehicle and Motorcycle Association). Full nameplate-level data and the kei share trend sit on the Japan dashboard.