Nissan Motor Company said on Thursday it is looking at ways to protect jobs at its US plants but declined to elaborate on what it will do if its appeal to be exempt from fuel-economy rules is rejected.
Japan's third-largest auto-maker has about 13,400 employees in the United States.
US rules set fuel economy standards separately for imported models and those made in the United States.
Under the North American Free Trade Agreement (NAFTA), Nissan's Sentra model, which is made in Mexico, will from 2005 be regarded as a domestic model instead of an import.
That will result in Nissan facing heavy fines, because the Sentra is far more fuel-efficient than its other models imported into the US, and it would fall foul of the rules.
It filed a petition with the US highway safety agency in January.
"We've listed possible scenarios with NHTSA, and we will make a decision at some point if and when the petition is not granted," a Nissan spokeswoman said, referring to the US National Highway Traffic Safty Administration.
"But we cannot comment on those plans at this time."
The Wall Street Journal reported on Thursday that Nissan wrote in its request that without an exemption it might cut US production of Altima or Maxima cars, which it said could lead to reduction in employment at its US plants.
It produces about 142,000 Sentras annually, and last year sold 94,500 in the US and about 30,000 in Mexico.