Clean Car Campaign

fuel economy improvement technologies | hybrids | advanced technologies | clean car standard

Fuel Economy

Improving fuel economy is fundamental to addressing many of the environmental problems associated with motor vehicles. A variety of options exist for improving fuel economy, ranging from numerous refinements in existing designs to advanced technologies that offer larger leaps forward in efficiency. Among the most exiting recent developments in automotive engineering is the fact that some of these "leap forward" advanced technologies are ready for widespread commercialization. The resulting designs offer a 50% or higher improvement in fuel economy for a given size or style of vehicle without compromising utility, safety, or performance.

Hybrid powertrains combine the range and power of an internal combustion engine with the high efficiency of electric drive. Conventional auto engines are least efficient at low loads, whenever the vehicle is not accelerating rapidly or climbing a hill at freeway speeds. A hybrid powertrain allows the engine to be sized and tuned for higher efficiency under these common driving conditions, with an electric motor providing extra power from a battery as needed to meet peak loads. Because a hybrid drivetrain has a battery (or other energy storage device) along with power electronics that manage motor and generator components connected to the wheels, it can also recapture braking energy that would otherwise be lost. This regenerative braking ability serves to further increase fuel efficiency.

The world's first mass-produced hybrid vehicle was the Toyota Prius, a 4-door sedan. Introduced to the Japanese market in December 1997, the Prius reached U.S. showrooms in 2000 achieving over 50 mpg in city driving, and reaching the stringent California SULEV emission standards. The first hybrid available in the U.S. was the 2-door Honda Insight. The Insight achieved fuel economy of over 70 mpg on the highway, and reaches ULEV emission standards. The next hybrid vehicles to be introduced included the Honda's 50 mpg Hybrid Civic (2002) and Ford's 36 mpg Escape Hybrid (2004). In 2004 and 2005, several more hybrid vehicles will be introduced to U.S. consumers, including hybrid versions of the Honda Accord, Lexus RX330 and Toyota Highlander.

In short, a number of advanced technology options now exist that can be applied to provide at least a 50% boost in fuel economy while maintaining size, safety, performance and capacity and also meeting very low emissions standards (ULEV or better). Hybrid drivetrains are one promising approach to achieving such efficiency improvement, but a similar degree of environmental excellence can also be attained with a lightweight, streamlined structure and an incrementally improved gasoline engine. All of these technologies are applicable across the size spectrum of the car and light truck market. Thus, the Clean Car Campaign's specification of a 50% increase in fuel economy is a target that we expect any one of the major automakers could reach in the near-term.