Depends on whether the hybrid is used for city or highway driving. The savings are quite high for stop-and-go city driving because the engine automatically shuts off when the car is stopped. If all current vehicles were magically converted into hybrids today, the result would be a huge drop in the price of oil. There are other strategies for improving gas mileage that may compete with hybrids...
Car Makers Seek New Spark In Gas Engines
By NORIHIKO SHIROUZU
Staff Reporter of THE WALL STREET JOURNAL
September 28, 2004; Page B1
With oil prices hovering above $50 a barrel, some of the world's major auto makers are accelerating efforts to improve the fuel efficiency of cars without resorting to expensive batteries or hybrid gas-electric systems.
Their goal: to enhance today's gasoline-engine technology so that cars can travel vastly more miles per gallon of fuel.
"Even the best of today's most advanced gasoline engines on average waste more than 80% of the [thermal] energy they create by burning gasoline," Honda Motor Co. Chief Executive Takeo Fukui says. "We think possibilities for improvement are almost infinite there."
Archrival Toyota Motor Corp. has a similar goal. "Everybody wants to double the efficiency of gasoline engines , and we are all working on similar technologies," says Masatami Takimoto, chief of Toyota's power train development in Japan. "Most likely it's going to be a dead heat."
At General Motors Corp., engineers are working on a new type of gasoline internal-combustion engine that could provide "80% of the efficiency of a hybrid or a diesel for 20% of the cost," says Scott Fosgard, a GM spokesman.
Underlying many of these efforts is a renewed interest in a technology automotive engineers call "homogenous-charge compression-ignition," or HCCI. The technology, which is believed capable of providing as much as a 30% boost in the fuel economy of a gasoline engine , is a hot topic in automotive research labs at GM and Ford Motor Co. in the U.S., Volkswagen AG and DaimlerChrsyler AG in Germany, and Toyota, Nissan Motor Co. and Honda in Japan.
Mechanically, an HCCI engine , like a conventional gasoline engine , sends a finely balanced mixture of air and fuel to the cylinders. In a conventional gas engine , a spark plug ignites the air-fuel mixture to create power. But in an HCCI engine , the air-fuel mixture is compressed by the piston until rising heat inside the chamber ignites the mixture -- a process similar to that used in a diesel engine.
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