"We are firmly opposed to the hasty introduction of measures such as a mileage tax without public discussion," said Seiichi Nagatsuka, vice chair of the Japan Automobile Manufacturers Association.

Japan's Finance Minister Shunichi Suzuki floated the plan among the ideas he mentioned in a parliamentary debate last month to tackle a severe financial situation.

(Reporting by Satoshi Sugiyama; Editing by Clarence Fernandez)