Super Ultra Low Emission Vehicle (SULEV) is a U.S. classification for conventionally powered, natural gas powered, or gasoline-electric hybrid vehicle designed to produce minimal emissions of certain categories of air pollution at their exhaust, typically 90% less than that of an equivalent ordinary full gasoline vehicle for the controlled pollution categories.
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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 fuel economy in severe city driving. A vapor tight fuel tank and system eliminate one source of hydrocarbon emission. Special catalytic converters called three-way catalytic converters reduce all three of the target pollutions from the exhaust pipe.
Examples of hybrid vehicles delivering SULEV emissions performance include the Honda Insight.
The Toyota Prius is no longer eligible for the California Clean Air Vehicle sticker. It is not a SULEV.
A conventionally powered example is the Ford Focus SULEV variant. In 2005, General Motors' 3800 Series III V6 engines became the industry's first gasoline V6s to carry the SULEV rating and can be found in the Pontiac Grand Prix (optionally supercharged), Buick LaCrosse, and the Buick Lucerne.
Honda's 2006 Civic Hybrid is another example of a SULEV vehicle, in addition to getting almost 45 miles per US gallon (5 L/100 km; 54 mpg-imp). Honda was one of the first car makers to offer SULEV vehicles, starting with 2000 model year Honda Insights (Though only the CVT version attained this rating. The manual transmission version, due to its Lean burn, got a ULEV), one model of the 2000 Honda Accord (special SULEV version of the EX 4-cylinder model, available in California) and the Natural Gas powered Honda Civic GX.
Honda's factory built Civic GX model, which runs on compressed natural gas (CNG), remains in a category by itself. In years past it has been rated the cleanest internal combustion engine on the road, achieving an Advanced Technology Partial Zero-Emissions Vehicle SULEV (2) rating. Made in Honda's East Liberty, Ohio, plant, it was introduced for fleet-purchase only in the 1998 model year but has since been available to all consumers.
BMW's SULEV 325i, 325Ci, and 325iT were introduced in the 2003 production year with the BMW M56 motor to meet new emission requirements. The updated 2.5 liter engine, designated M56B25, was produced between 2002 and 2005. It was the first BMW SULEV.
The M56B25's power output and vehicle performance was the same as the comparable model equipped with the M54B25 engine (US only: BMW M54). The M56 SULEV models listed above were sold in California, New York, and Massachusetts as 2003 models and in Vermont starting in the 2004 model year.
In addition, these BMW vehicles were certified as Partial Zero Emission Vehicles (PZEV): they meet the SULEV tailpipe emission standard, which is approximately 1/5 of the ULEV standard, and they conform to the Zero Evaporative Emissions requirements.
PZEV is a more stringent variant of the SULEV standard. The Hyundai Elantra PZEV, the Subaru Legacy, Forester and Outback 2.5i PZEV, the Volkswagen GTI 2.0L Turbo PZEV, and the Volkswagen Jetta 2.5 PZEV are available in the U.S. state of California in compliance with this standard. Lexus introduced the Lexus RX400h luxury SUV in 2006 with the SULEV rating. Lexus marketed the LS600h L sedan in 2007 delivering SULEV performance.
Many SULEV vehicles are only available in LEV-II states. These include California, New York, New Jersey, Vermont, and Massachusetts.
In the 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 a Partial Zero-Emission Vehicle (PZEV). 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 (15-year/150,000-mile (241,000 km)) warranty on its emission-control components.
In the case of hybrid vehicles this warranty is extended to the electric propulsion components (electric motor/generator/starter, battery, inverter, controls) and their mechanical interface to the driveline - potentially a distinct advantage to the owner of such a vehicle.
See California AB 1493 [1].