With concerns about greenhouse gas emissions and limited fossil fuels availability, U.S. government regulations, such as the Corporate Average Fuel Economy (CAFE), have been put in place since 1975 to regulate the fuel economy of cars and light trucks. More recently, in June 2015, the Environmental Protection Agency (EPA) and the Transportation Department drafted new carbon-emissions standards for big trucks, which mandate that all big trucks built in 2021 or after must be as much as 24 percent more fuel efficient and emit as much as 24 percent less carbon emissions than an equivalent truck built in 2018. Similar regulations and recommendations are being made throughout the world.
Automotive manufacturers and their suppliers are exploring many different approaches for increasing fuel economy of gas- and diesel-powered vehicles. An important area of focus is the reduction of energy losses associated with friction, often referred to as parasitic energy losses. Fuel efficiency increases as more energy becomes available to propel the vehicle and less energy is wasted on frictional losses. Currently, less than 15% of fuel energy is converted to useful energy that drives the vehicle and roughly 10% of energy input is consumed by friction. The development of engineered surfaces of automotive components with low-friction and controlled surface topography has been reported to improve fuel efficiency by 3-5%. There are huge benefits from even a few percent of improvement in fuel efficiency considering the relatively low energy conversion rate of gas- and diesel-powered vehicles. For example, in the United States, a three-mpg increase in fuel economy would save one million barrels of oil per day, save consumers as much as $25 billion per year in fuel costs, and cut carbon dioxide emissions by 140 million tons per year, according to a 2010 U.S. EPA press release.