The PZEV emissions category derived from an agreement between automakers and the California Air Resources Board that allowed postponement for zero emission vehicles, or ZEVs, such as hydrogen fuel cell or electric vehicles. Automakers were not prepared to mass-produce all-electric vehicles because they were cost prohibitive. The compromise allowed auto manufacturers to produce cars that satisfied PZEV and SULEV guidelines. Another category is the AT-PZEV for Advanced Technology for vehicles consuming no diesel or gasoline. The Honda Civic GX, which runs on natural gas, falls in this category.
PZEV cars are Partially Zero Emission Vehicles. These vehicles have “zero evaporative emissions” in their fuel systems and feature a 15-year and/or 150,000-mile guarantee for all emission control components. The warranty also must cover the electrical components, such as parts in a hybrid vehicle. The state of California has a specific low emissions category for PZEVs.
The PZEV follows other standards or is similar to other emission control guidelines implemented by the state of California. An early version was the Transitional Low-Emission Vehicle, or TLEV, that ended in 2004. The Low-Emission Vehicle standard, or LEV, began in 2004. A separate, Ultra Low-Emission Vehicle, or ULEV, which is not as rigorous as the PZEV, categorized vehicles that were 50% cleaner than standard automobiles. In contrast, the SULEV designated vehicles that had 90% fewer emissions than standard automobiles. The PZEV category is the second-most stringent standard with zero evaporative emissions. However, the Zero-Emissions Vehicle, or ZEV, tops all categories with zero harmful tailpipe emissions and runs 98% clean than the average new vehicle model.
The Air Resources Board certifies each car sold in California, using a Smog Score table that measures non-methane organic gases and oxides of nitrogen and sulfur, or NOx, from the vehicle’s tailpipe that evaporates into the air. The table measures grams per mile. ZEVs measure no non-methane organic gases or NOx grams per mile, giving such vehicles a perfect 10. PZEVs, AT-PZEVs and SULEVs earn a 9 score for having 0.030 grams per mile. However, a SULEV medium-duty truck earns a 3 score for having 0.190 to 0.200 per mile.
Among the cars that earn a PZEV designation are the Honda Accord EX and the Toyota Prius hybrid. PZEV can use gasoline, but they produce fewer emissions while being driven. Honda and Nissan were early producers of PZEV. Nissan, for example, manufactures PZEV-certified Altima and Sentra sedans. The Altima PZEV features a four-cylinder engine that has a reduced output from 175 to 170 horsepower to meet PZEV standards. The Honda Accord EX uses a 2.4-liter four-cylinder engine. These versions are sold in Northeast North America and California. Subaru also produces the all-wheel drive Outback PZEV. Since 2004, BMW, Dodge, Ford, Chrysler, Mazda, Volkswagen, Volvo and Mitsubishi have followed Honda and Nissan in producing PZEV cars.
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