A little boy urinating might not easily conjure up images of a cleaner world, but Honda had other ideas Thursday as it tries to promote its green-car technology.

The Japanese firm erected a two-metre (6.6 foot) replica of famous Brussels landmark Manneken Pis -- the bronze statue of a boy peeing into a fountain -- for its display at the Tokyo Motor Show.

The not-so-little plastic "Piss Boy", as the famous statue is known in Japan, was meant to show how the company's fuel-cell technology works, earning it the moniker "Hydrogen Boy".

A hydrogen tank is strapped to his back.

"When hydrogen and oxygen go into a fuel cell, they react chemically and generate power," the boy's recorded voice tells passersby in Japanese, his eyes flashing as he urinates into a pool below.

"But only water comes out. Dribble, dribble."

Honda said Thursday it would roll out a commercial fuel-cell vehicle in 2015, a day after rival Toyota promised a similar offering as competition in the sector heats up.

Fuel-cell vehicles are considered the holy grail of green cars because they emit nothing but water vapour from the tailpipe and can operate on hydrogen produced using renewable methods.