5 Quick Facts About PZEVs

A partial zero emissions vehicle on a platform at an auto show.

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Partial Zero Emissions Vehicles, or PZEVs, are vehicles with engines that have been equipped with advanced emissions controls. This results in zero evaporative emissions.

You may have heard about vehicles with the PZEV designation. For example, the 2012 Honda Civic Natural Gas, also known as the 2012 Honda Civic PZEV, has a natural gas engine with almost zero pollution-forming emissions. It's been identified as one of the cleanest internal-combustion vehicles to receive certification through the U.S. Environmental Protection Agency. The state of California has recognized this special Honda Civic model with Advanced Technology Partial Zero Emissions Vehicle, or AT-PZEV, designation because it meets that state's stringent emissions control standards. It also has a warranty to maintain its emissions for at least 150,000 miles or 15 years.

PZEVs Are Rooted in California

PZEV is an administrative category for low emission vehicles in the state of California and other states that have adopted California's more stringent pollution control standards. The PZEV category began in California as a bargain with the California Air Resources Board to allow automakers the ability to postpone mandated zero emission vehicles, due to the cost and time necessary for electric or hydrogen fuel cell vehicle production. Vehicles that have been manufactured to meet PZEV requirements outside the state of California are usually referred to as super ultra-low emission vehicles, sometimes abbreviated as SULEVs.

They Must Meet Specific Standards

Certified vehicles must meet tight emission test requirements for volatile organic compounds and oxides of nitrogen, as well as carbon monoxide. Emissions-related components must be warranted for 10 years or 150,000 miles, including electrical components of hybrid and electric cars. Evaporative emissions must be zero. When the California standards were being formulated, it was anticipated that battery-powered cars would be much more readily available soon after the new standards were adopted. Because cost and other factors kept the number of electric cars dotting the highway to a lower number than expected, a modification of the original mandate gave birth to the PZEV. This allowed car manufacturers to meet requirements through partial zero credits.

The Name Refers to Emissions, Not Fuel Efficiency

Don't confuse PZEVs with vehicles that rate above-average for fuel efficiency. PZEV refers to vehicles with advanced emission controls, but that does not equate with improved fuel efficiency. Most PZEVs come in at about average for their class in fuel efficiency. Hybrid or electric vehicles that meet PZEV standards are sometimes classified as AT-PZEV for Advanced Technology PZEV because emissions are just as clean, but they get much better fuel efficiency.

The Standards Demand Compliance

Under the Clean Air Act, California was able to set more stringent vehicle emissions standards, including tailpipe emissions. In 2009, car makers were charged with reducing greenhouse gas emissions for new passenger cars and light trucks. Automakers were given eight years to bring new vehicle manufacturing in line to cut pollutants by approximately 30 percent once fully phased in by the end of 2016.

Expect to See More

While PZEVs and the low emissions movement got its start in California, other states have since followed in the Golden State's footsteps. The stricter standards aimed at cutting emissions by approximately 30 percent by 2016 were adopted by multiple states, as well as the District of Columbia. Similar standards are also part of an agreement Canada signed with automakers.