The EPA issued this statement to Dateline NBC in regards to the fuel-saving device investigation Dateline did.
The U.S. Environmental Protection Agency oversees a program to evaluate aftermarket devices and fuel additives for cars and light duty trucks that are intended to improve fuel economy or reduce emissions. A manufacturer may contact us if they wish to participate in this voluntary program. EPA has tested a number of these aftermarket devices over the years. And, to date, have found they generally do not work. EPA has does have proven tips to help motorists improve their fuel economy.
More information is available at fueleconomy.gov.