A trade group representing Detroit's Big Three automakers and Toyota Motor Corp. urged the Obama administration to reject efforts by environmental groups and 18 senators to impose a 62 mpg requirement by 2025.

The administration said it is considering annual increases in fuel efficiency ranging from 3 to 6 percent between 2017 and 2025, which equates to a fleetwide average of 47 mpg and 62 mpg by the period's end. The range of costs per vehicle is $770 to $3,500, depending on the stringency, reported The Detroit News.

Last month 18 senators led by Dianne Feinstein, D-Calif., and Olympia Snowe, R-Me., sent a letter to Transportation Secretary Ray LaHood and Environmental Protection Agency administrator Lisa Jackson urging them to adopt 62 mpg by 2025.

"A significant increase in fleetwide fuel economy - six percent annually - is both technically feasible and cost effective for consumers," they wrote.

The Alliance of Automobile Manufacturers - the trade group representing General Motors Co., Ford Motor Co., Chrysler Group LLC, Toyota and eight others - said in a letter the administration should set the targets based on analysis.

"Fuel economy and greenhouse gas targets should not be arbitrary numbers, chosen before the necessary analyses are completed," the group's interim chief John Whatley wrote in a letter to LaHood and Jackson made public today. That "would circumvent the rulemaking process and undermine the ongoing collaborative effort to set sound standards."

Automakers noted that 1.7 million direct jobs come from the auto industry. They cited an Energy Information Administration forecast released in April projecting that setting fuel economy requirements at 62 mpg in 2025 "would reduce sales by 14 percent."

Automakers argued that could lead to a 14 percent reduction in jobs - or a loss of almost a quarter million jobs. Automakers' health "depends on reasonable regulations that provide clarity and certainty, without pricing our customers out of the market or preventing them from choosing vehicles that can meet their diverse needs."

Automakers have been holding private meetings with California and federal officials in an effort to hammer out an extension of a national fuel efficiency policy in recent weeks.

A 2007 Supreme Court decision opened the door to California imposing its own tailpipe emissions limits. The prospect of state and federal emissions limits has been harshly criticized by automakers.

In the wake of the decision, the Obama administration reached a deal with California and automakers in May 2009 to set nationwide standards for the 2012-16 model years that will hike fleet-wide fuel efficiency to 34.1 mpg by 2016. The deal essentially extended California's proposed standards nationwide, but gave automakers additional flexibility in early years.

California's standards were adopted by a dozen other states.

The measure will cost the auto industry $51.5 billion over five years, but also save 1.8 billion barrels of fuel over the life of the vehicles.

The Obama administration says it would save $3,000 per vehicle in gas over the life of the vehicles.

The administration is working on the 2017-2025 regulations and California is also working on its own proposal. Both proposals are to be issued in September, but officials said it could be delayed.