The choice may soon be yours: gasoline or natural gas. General Motors is planning on becoming the first car manufacturer to sell a dual-fuel-powered vehicle that can run on either conventional gasoline or compressed natural gas (CNG). Sources say GM CEO Dan Akerson will unveil GM's plans at the Securing America's Future Energy Conference in Washington.

According to sources, GM has been looking at such a vehicle for "some time". Indications are that GM isn't planning on this being their hottest seller, but over time, volumes will build.

GM is not yet putting a price tag on the dual-fuel vehicle, which is projected to go on sale next summer. The automaker is estimating it will have a range of roughly 150 miles using CNG and another 350 miles using gasoline. The driver will be able to switch between the two fuel tanks even in the middle of driving.

GM CEO Akerson has long supported developing natural gas powered vehicles, and a few weeks ago GM said it plans to sell dual-fuel compressed natural gas versions of the 2015 Chevrolet Silverado and GMC Sierra pickups. While the automaker hasn't yet released a price for those trucks, previous versions of CNG-powered pickups have gone for over $10,000 more than their gasoline powered counterparts.

The high costs, along with the lack of public natural gas refueling stations, are reasons automakers have been slow to expand their lineups to include CNG vehicles. There are just over 600 publicly available CNG stations in the U.S. versus more than 120,000 gas stations.

However, natural gas powered vehicles may resonate with Americans on their benefits: far fewer emissions vs. gasoline vehicles and plentiful supply of natural gas, thus reducing the price to fill up. A gallon of gasoline in major cities this summer hit over $4/gallon while the equivalent volume of natural gas sold for just $2.15.