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Super Ultra Low Emission Vehicle (SULEV) is a conventionally powered or gas-electric hybrid vehicle designed to produce minimal air pollution, typically less than 10% of that of an equivalent ordinary vehicle.
Controlled pollution categories are:
Several techniques can be used to reduce pollution. Since automobiles most heavily pollute when warming up the catalytic converter, moving this closer to the engine (or even heating it electrically) will enable it to quickly become effective. Preheating the cylinder head from previously saved hot coolant is used in some vehicles. Careful management of engine shut down is required to eliminate uncombusted fuel. Engine shutdown while the vehicle is stopped, rather than idling the engine, not only reduces pollution but can greatly improve mileage in severe city driving. A vapor tight fuel tank and system eliminate one source of hydrocarbon emission. Special catalytic converters called three-way reduce all three of the target pollutions from the exhaust pipe.
An example of a hybrid vehicle delivering SULEV emissions performance is the Toyota Prius. A conventionally powered example is the Ford Focus SULEV variant.
In the U.S. State of California, manufacturers of SULEVS can be given a partial credit for producing a Zero Emission Vehicle (ZEV) and so a vehicle of this type can be administratively designated as PZEV (Partial Zero-Emission Vehicle). In order to qualify as a PZEV, a vehicle must meet the SULEV
standard and, in addition, have zero evaporative emissions from its fuel system plus an extended (ten-year/150,000-mile) warranty on its emission-control
components.
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