Guide to Near-Zero Emission Vehicles

In an era when the jargon of "bigger, better, faster" seems to dominate automotive advertising and sales talk in new-car showrooms, there's a shocking trend afoot. Environmentalism may have sneaked into the equation without so much as announcing its presence.

The Honda Accord EX driven off the lot in California has emissions so low they can barely be measured. A Toyota Prius gasoline-electric hybrid bought in New York brings with it extremely low emissions and an estimated combined 55 mpg fuel economy. And a 2004 Ford Focus sold in Massachusetts offers more power than its predecessor while delivering a few more miles to the gallon and nearly imperceptible emissions.

What are these amazing cars? "PZEVs," or Partial Zero Emission Vehicles. They run on everyday gasoline but give up few emissions along the way. PZEVs have come to us courtesy of California's Zero Emission Vehicle (ZEV) mandate, an integral part of the state's low emission vehicle program crafted back in 1990. While the ZEV mandate has gone through some fairly extensive shape-shifting over the years, it is still with us in a form that's bringing cleaner cars to California's highways and, by extension, yours as well.

The mandate was to bring a revolutionary change to the auto industry that would see massive numbers of battery electric vehicles plying California highways, and ultimately, the roads of America. Historically, California's stringent emissions laws have led to tighter federal regulations. But battery technology didn't cooperate. What we ended up with were great and efficient vehicles driven by electric motors – marvels of technology, really – with far too little onboard battery power to take them where they needed to go.

While it could be argued that marketing efforts were not adequately sustained and the major automakers' electric vehicles were around only long enough to fulfill their obligations to the state of California, there's still that bothersome bottom line: Electric vehicles cost way too much, they didn't go far enough on a charge, and automakers had a serious distaste for being required to build them at truly substantial losses. Ultimately, lobbying and legal maneuvering caused the ZEV mandate to be radically modified. This spelled the demise of the full-function electric vehicle, although the smallish, low-speed neighborhood electric vehicles that remain may be finding their niche.

This change also brought about new types of vehicles that would allow automakers to make their quotas of ZEVs through ultra-clean vehicles, which would provide partial ZEV credits. The PZEV was born – first coming to us from Nissan and Honda, then from a growing array of automakers that realized others were on to something important.

What makes a car a PZEV? The California Air Resources Board defines automobiles that receive a Partial Zero Emission Vehicle (PZEV) credit as being ones that have met the state’s Super Ultra Low Emission Vehicle (SULEV) tailpipe standard, which is 90% cleaner than the average new 2004 automobile. In addition, a PZEV must have near-zero evaporative emissions and its emission control equipment must carry a 15-year/150,000 mile warranty. To be rated as an Advanced Technology Partial Zero Emission Vehicle (AT-PZEV), an automobile must meet all the above criterion for a PZEV rating and additionally must make use of "ZEV-enabling clean technology” such as alternative fuels, electric drive, or other advanced technology systems.

Today, PZEV models are being made by BMW, Chrysler, Dodge, Ford, Honda, Mazda, Mitsubishi, Nissan, Subaru, Toyota, Volkswagen and Volvo. Some offer a single PZEV model equipped with a specific engine-transmission package, while others offer multiple models. Examples are Volvo with its S60 and V70, Subaru with its Legacy and Outback, and Honda with its Accord and Civic (the latter running on compressed natural gas).

In some instances, a car must be equipped with a specific engine to be a PZEV and it may be available only in some states. One example is the Honda Accord EX with its 2.4-liter engine, a PZEV package available in California, Maine, Massachusetts, New Jersey, New York, and Vermont. Another is the 2.3-liter Ford Focus, which comes standard as a PZEV in the aforementioned states, with the same engine and fuel system optional in all others.

It should be noted that even though the Prius and Focus are available with their same ultra-clean powerplants nationwide, they are technically SULEVs (Super Ultra Low Emission Vehicles) rather than PZEVs in most states since California’s cleaner gas formulation is not available. Additionally, the extended 150,000 mile emissions system warranty required for PZEV certification is typically not offered outside of California and the small handful of “green” Northeastern states.

Still, the importance of this emissions achievement is somewhat staggering. Automakers have shown they are capable of building the very vehicles that many people have hoped for, but thought were impossible. Normal, everyday cars. Cars that don't require an alternative fuel. Cars that drive about while leaving almost no emissions in their wake.

There is but one catch: The technology does come at a cost, which automakers generally don't care to quantify but is thought to be in the hundreds of dollars per car. While this doesn't seem a substantial sum, it is to carmakers, who think in terms of hundreds of thousands or even millions of units and who believe, rightfully so, that car buyers aren't likely to pay that extra cash to drive "green." In most cases this cost is being absorbed for competitive reasons, but there are some instances where a surcharge is being tacked on. Subaru, for instance, has raised the base MSRP of its Legacy and Outback PZEV models by $200.

For the most part, the introduction of these super-clean cars is happening in slow motion. Most are available only in California and a handful of Northeast states because that's where they net PZEV credits. However, this could change as demand for these cars rises, the required low-sulfur gasoline is more readily available, and automakers see a competitive advantage in rolling them out in other areas. Indeed, there’s every opportunity for PZEV activities to ramp up and additional models to be introduced because the value of these cars in fighting air pollution is just now being quantified.

A study sponsored by the U.S. Environmental Protection Agency, the California Air Resources Board (CARB), Honda R&D Americas, ChevronTexaco, and the Manufacturers of Emission Controls Association concludes that the Los Angeles Basin, one of the most polluted regions in the U.S., could more rapidly achieve federal air quality goals for smog through aggressive implementation of PZEVs that are currently available.

This conclusion comes from the final results of the Study of Extremely Low Emission Vehicles (SELEV), which was conducted over the past three years by the UC Riverside Bourns College of Engineering's Center for Environmental Research and Technology (CE-CERT). Using atmospheric modeling, the study found that greater use of the best existing, proven, gasoline engine and auto emission control technology could enable the Los Angeles air basin to reach 2010 ozone attainment goals. This assumed that by 2010, all passenger vehicles would be less than 15 years old and that all cars sold in 2004 and later would meet at least the current California SULEV standard. The university points out that these assumptions may not be entirely achievable, but that this line of thought provides a roadmap of what could be achieved through aggressive implementation.

"The impressive thing about these findings is that the technology and fuels that were developed for these clean cars to meet the California air standards will, within a few years, find themselves in the rest of the nation's fleet and then the rest of the world's fleet,” says Dr. Joseph Norbeck, CE-CERT director. Norbeck points out that the recipe for attacking smog is clean vehicles aided by clean fuels, adding that “if clean fuel is available we'll soon find that these cars will be able to help solve air quality problems in cities in China, India, Egypt and other air-quality challenged countries."

The SELEV study evaluated tailpipe emissions from ULEV, SULEV, and PZEV vehicles under real-world conditions to meet California's strict emissions standards. Over the course of three years, researchers drove the test vehicles in typical Southern California traffic in all types of weather conditions.

CE-CERT has successfully developed the measurement technology to test emissions at lower levels, most importantly vehicles that meet the state's stringent SULEV and PZEV standards. These vehicles must meet the increasingly stringent requirements for volatile organic compounds (VOC), oxides of nitrogen (NOx), and carbon monoxide (CO) on emissions certification tests.

Ultimately, Norbeck says, the PZEV’s potential could mean that "light-duty passenger automobiles will soon be taken off the 'most-wanted' list of air pollution sources." For cities like Los Angeles, Denver, Phoenix, Las Vegas, and many others that face serious air quality issues and heavy traffic as a matter of course, that could be tremendous news and a turning point in their historic fight with smog.

All this is not lost on automakers. With the number of PZEV models now approaching 20 and growing, this is no longer just a blip on the emissions radar. PZEVs are coming on strong. Even if vehicles equipped with these advanced engines and emissions controls don’t attain PZEV levels in all states, they are SULEV certified and extremely clean. It’s just a matter of time until the rest of the country catches up and we can all breathe a bit easier.