WASHINGTON - The Obama administration expects the new fuel- efficiency regulations announced April 1 to boost car and truck fuel efficiency, help reduce greenhouse gases, and save billions of dollars, according to the Detroit News.

Car and truck fuel efficiency will increase to 34.1 miles per gallon for a 40-percent boost in fuel economy, while greenhouse gases will be reduced by more than 30 percent by 2016.

On the downside for the automakers, some analysts say sales could drop if motorists, having paid more for their vehicles, hold on to them longer.

NHTSA predicts that passenger cars will have to average 33.3 mpg in 2012, and 37.8 mpg in 2016. Light trucks, including SUVs, pickups and vans, will be required to average 25.4 mpg in 2012 and 28.8 mpg by 2016.

The new regulations allow automakers to get credits for building flex-fuel vehicles, which run on E-85 or gasoline, until 2015. After that, they must show the alternative fuel is being used to get credits.

The government says the total value to society in reduced gasoline use and lower emissions will be about $240 billion, so the net benefit is about $190 billion.

Automakers that sold fewer than 400,000 vehicles in 2009 will be able to meet a less-stringent greenhouse gas standard. That will be limited to up to 100,000 vehicles total, spread over 2012-15, reported the Detroit News.