Kei Car vs Regular Car Running Cost Comparison
Enter engine displacement, annual mileage, gasoline price, and fuel efficiency to compare the annual running costs of a kei car (Japanese light vehicle) and a regular/compact car, including automobile tax, weight tax, compulsory insurance, and fuel cost.
Tips
- The engine displacement and vehicle weight for a regular car are printed on the vehicle inspection certificate (shaken-sho). If you're unsure, a compact car is typically 1.0-1.5t and a minivan or SUV is typically 1.5-2.0t.
- For a more realistic comparison, enter real-world fuel efficiency (calculated from fuel purchased and distance driven) rather than the catalog (WLTC-mode) figure.
- The shorter your annual mileage, the smaller the fuel-cost gap becomes, which makes the tax and insurance advantage of the kei car relatively more significant.
- Kei cars also tend to have a lower purchase price and lower voluntary insurance premiums, but those are not included in this estimate, so factor them in separately when comparing total cost of ownership.
Frequently asked questions
Side Note — Why is the kei car limit set at 660cc?
The current 660cc displacement limit for kei cars was set in a 1998 regulation revision. Before that it was 550cc (from 1976) and, further back, 360cc when the category was first created in 1949. The standard has expanded in stages over the decades alongside improvements in safety and emissions technology, but its origin lies in giving ordinary households in postwar Japan an affordable way to own a car.
Kei car tax breaks extend beyond the weight tax, which is a national tax, to the kei car tax itself, which is a local tax collected by municipalities. Regions where kei cars are more heavily relied upon for everyday local transportation tend to have higher kei car ownership rates, and the kei car tax is a familiar, steady revenue source for many local governments.
Modern kei cars have closed much of the safety and fuel-efficiency gap with regular cars thanks to years of engineering improvements. That said, body size limits still cap passenger capacity and cargo space, so choosing between a kei car and a regular car should weigh not just running costs but also whether the vehicle actually fits your intended use.