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The General Motors Precept, a groundbreaking low-emission vehicle concept introduced in 2000, aimed at achieving an impressive 80 mpg‑US fuel economy goal. This ambitious endeavor was part of the Partnership for a New Generation of Vehicles, a collaboration between the US Government and major automakers such as GM, Ford, and Chrysler.
The Precept showcased GM's commitment to innovation, offering various versions utilizing Lithium and NiMH batteries combined with diesel, fuel cell, and hybrid technologies. GM successfully met the 80 mpg‑US fuel economy target with the Precept, demonstrating versatility and ingenuity in its approach.
Despite achieving this remarkable feat, GM concluded the Precept project in 2000, citing a perceived lack of consumer interest in high-fuel economy vehicles. The near-term PNGV program, initiated during the Clinton Administration, faced termination under the Bush administration, giving way to the distant goals of the FreedomCAR vehicle program.
While the Precept was not intended for production, it was a testing ground for innovative ideas that could influence future developments. Some concepts from the Precept potentially contributed to GM's later "dual-mode" hybrid system, showcasing the company's commitment to advancing environmentally friendly technologies.
The Precept's unique powertrain featured two 35 kW electric motors strategically placed on the front and rear axles. The rear axle was connected to a diesel engine or another power source, which could directly drive the rear wheels or generate power for the front-wheel motor. This design allowed for flexibility in different driving scenarios, seamlessly combining electric and diesel power.
The GM "dual-mode" hybrid system evolved from the Precept's powertrain, adapting its principles into a more versatile and scalable solution. By conceptualizing the Precept's two-axle system into a "dual-mode" drivetrain for large vehicles, GM showcased its ability to innovate and adapt cutting-edge technologies for broader applications.
The Precept concept was not just about fuel efficiency; it embodied an ultra-high-efficiency, environmentally friendly architecture. With a remarkable drag coefficient of 0.163, it boasted the most aerodynamically efficient design at the time. The four-wheel-drive, dual-axle configuration featured a 35-kilowatt three-phase electric motor driving the front wheels, coupled with a lean-burn compression-ignition, direct-injection heat engine propelling the rear wheels.
Source: Wikipedia; www.autospeed.com Images: GM