In August 2012, the Obama Administration had decided to increase the fuel economy for cars and trucks to 54.5 miles per gallon by 2025. It would save about $1.7 trillions for the consumers and decrease U.S oil usage by 12 billion barrels. About 70-72 percent of engine losses is from radiator and exhaust heat. We lose 17-21 percent of fuel on wheels rolling through brakes and resistance. About 5-6 percent of fuel usage is lost from water pumps and alternator. More mileage will boost the economy by four or five miles per gallon. Some car businesses like Ford and Altima have adapted to the new gas mileage technology.

There are many ways automobile industries increase gas mileages. GM has called Cylinder Deactivation a Displacement on Demand. During cruising speed, an ICE(Internal Combination Engine) works on thirty percent of power that partially opens the throttle valve. A throttle is fluid managed by constriction or obstruction. This limits the movement of fuel and air, which makes engine harder to take in air. When four out of eight cylinders are shut during cruising, it completely opens the throttle valve and helps the engine breathes. Cylinder Deactivation saves twenty-eight percent of fuel. Turbocharging is a second method to increase gas mileage. It expands the amount of air and fuel that’s burned and captures the wasted energy. The wasted energy is forced to spin a turbine that pushes clean air in the engine’s manifold; creates torque and horsepower. Horsepower helps the small engine to accelerate power.
Direct fuel injection is the third method to enlarge mileage. However, this method uses advance computer management that calculate a precise amount of fuel injected. Air reaches the cylinder through manifold and fuel is placed separately in the cylinder. More fuels are burn and produces a finer mist.
The fourth approach to expand gas mileage is Homogenous Charge Compression Ignition (HCCI). HCCI is used with diesel engines because they use heat made by compression to ignite fuel-air mixture. GM says HCCI saves up to fifteen percent that may provide fuel economy.

References:

1. http://www.usnews.com/news/blogs/rick-newman/2012/08/27/tough-government-gas-mileage-rules-good-for-drivers-auto-industry

2.http://www.bankrate.com/finance/auto/hybrids-not-the-only-answer-2.aspx

3.http://www.stltoday.com/business/local/auto-industry-makes-strides-toward-improving-fuel-economy/article_2d050408-95db-561b-97fc-b84c708829d4.html