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.
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.
External links
List of CARB SULEV qualifying vehicles (http://www.arb.ca.gov/msprog/CCBG/2004pc.htm)
BMW SULEV models (http://www.bmwworld.com/models/years/2003/sulev.htm)
University of California study - effect of rapid introduction on Los Angeles meeting smog standards (http://www.prnewswire.com/cgi-bin/stories.pl?ACCT=104&STORY=/www/story/09-23-2003/0002022176&EDATE=)
SULEVs and PZEVs are cars whose emissions are so low that if you run them in a major metropolitan area the air coming out of their exhaust pipe is actually cleaner than the air you're breathing.
SULEV cars which are not gas-electric hybrids and burn the sulfur-bearing gas available in most states may not meet full SULEV standards while burning that gas, though they still qualify as ULEVs at 90% lower emissions.
Of course, the spread of SULEVs as the standard nationwide may be interrupted by the growth in popularity of gas-electric hybrid vehicles which meet the PZEV standard, so their emissions are as low or lower, plus they get much better gas mileage.
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