PARIS -- Chief executives from 13 of the world's top automakers pledged to jointly press for global standards on car safety and environmental regulations, saying it would reduce emissions and cut costs.

In a joint statement, issued after a meeting they touted as unprecedented, the CEOs said it was "critical" for them to work together on three main issues -- international harmonization of vehicle regulations, worldwide acceptance of clean diesel technology and the promotion of advanced technology and improved fuel quality worldwide.

The rare expression of unity, in a fiercely competitive business where car bosses fight brutal daily battles with their rivals for market share, took place on the sidelines of the Paris auto show.

The low-profile meeting, in a hotel near the auto show venue, came against the backdrop of growing international scrutiny of the auto industry and what environmentalists see as an almost criminal contribution to global warming through greenhouse gas emissions from cars and trucks.

"International harmonization of technical regulations for motor vehicles will improve safety, protect the environment, and reduce costs for consumers around the world," the automakers said in a joint statement.

In the statement, issued by the major automotive trade groups in Europe, Japan and the United States, the automakers vowed, among other priorities, to seek greater world acceptance of clean diesel technology and greater availability of low sulfur or "sulfur-free" fuels, Reuters reported.

They also called for improvements in the quality of gasoline fuels and stepped up efforts to promote the development and sale of advanced technology vehicles such as hybrid electrics and fuel cell vehicles.

*** First Step**** "There are areas where we all think (harmonization) would make sense and make the industry improve faster," said GM chief executive Rick Wagoner as he emerged from the meeting.

He called the summit a first -- albeit tentative -- step toward greater cooperation in the industry.

Known for fighting bitterly over every tenth of a percent of market share, automotive chief executives are rarely seen with a competitor, much less cooperating with more than a dozen other car firms.

"There are national differences. It's a question if we can really pick up the pace," Wagoner added.

Many jurisdictions, such as California, have air quality regulations that do not allow certain clean diesel technologies, which the group sees as an impediment to improved fuel economy and hence reduced greenhouse gases.

"Current diesel engines are dramatically more efficient than conventional gasoline engines in terms of both fuel economy and carbon dioxide emissions. Diesel engines also have the potential to meet stringent requirements regarding local emissions," they said.