Hybrid. Electric. Low emission. And no emission.


Drivers may be a bit fuzzy on the technical details, but they understand the basic concept of cleaner and greener methods of transportation. Now, add PZEV to the list. P what?


Chances are, if you’ve even heard of PZEV, you probably don’t know what it means. The “EV” in the term PZEV doesn’t stand for “electric vehicle,” as we’ve come to know the acronym. Instead, PZEV stands for Partial Zero Emission Vehicle.


If driving as green as possible is important, a PZEV-certified vehicle may fill the bill. The good news is that Subaru makes PZEV-certified vehicles. Fact is, Subaru has been offering PZEV-certified vehicles since model year 2004.


This California rating means a vehicle meets California’s Super-Ultra-Low-Emission Vehicle (SULEV) exhaust emission standard.




How PZEV Works


Just how green is a Subaru PZEV vehicle? Cutting your lawn with a gas mower puts out more pollution in one hour than these cars do in 2,000 miles of driving, for instance. As the California Air Resources Board (CARB) has noted, the tailpipe emissions of PZEV-certified vehicles can be cleaner than the outside air in smoggy cities. That’s amazing stuff.


The differences between non-PZEV and PZEV-certified Subaru vehicles can be found in three areas:

  • The catalytic converter
  • The Engine Control Module (ECM) programming
  • The fuel injectors


The catalytic converter for a PZEV engine has a finer mesh and higher volume of precious metals – platinum, palladium, and rhodium – than the standard converter, as well as twice the effective cleaning surface. This improves the converter’s performance as it reduces gases in the exhaust exiting the tailpipe.


In addition, the revised ECM programming delays ignition timing, which helps the catalytic converter heat up to operating temperatures sooner, thereby reducing cold-start emissions.


Finally, the engine’s precisely controlled fuel injectors close tighter than conventional injectors. This helps to prevent evaporative emissions from fuel leakage into the intake manifold and wasteful evaporation.


Bottom line: PZEV vehicles produce the lowest amount of tailpipe (greenhouse) emissions of any gasoline-only engine.




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