Last year, five automakers -- BMW AG, Ford Motor Co, Renault SA, Toyota Motor Corp and DaimlerChrysler, as the German automaker was known then -- made the list.

Nissan announced a medium-term environmental action plan last year focused on reducing carbon dioxide emissions, including a pledge to cut emissions at its factories by 7 percent in 2010 from 2005 levels.

The Carbon Disclosure Project surveyed about 2,400 companies worldwide this year, choosing 68 for the index.

Nissan has been trying to reverse its image as an environmental laggard to Toyota and Honda Motor Co, the leading makers of gasoline-electric hybrid cars.

In a separate report, US-based environmental lobby Union of Concerned Scientists (UCS) this month chided Toyota for its "two-faced" approach, based on its opposition to a provision in the Senate energy bill that would improve vehicle fuel economy.