Explaining the Meaning of PZEV with the 2012 Subaru Impreza Premium PZEV
We might assume that the “EV” in “PZEV” stands for “electric vehicle” as we all have come to know the acronym. Instead, PZEV actually stands for Partial Zero Emissions Vehicle.
On the 2012 Subaru Impreza Premium PZEV, there’s a shiny symbol on the trunk with PZEV sprouting a leaf. Most would assume, when seeing it for the first time, that the vehicle is an electric-hybrid of some sort. So what does the term PZEV mean? A partial zero emissions vehicle has a PZEV engine or drive train that meets or exceeds specific requirements set forth by the State of California.
So taking the 2012 Subaru Impreza Premium PZEV as an example, the vehicle gets 27 mpg city and 36 mpg highway while sporting all-wheel drive but it puts out 90% less emissions than its equivalent counterpart. As a result, it meets federal super ultra low emission vehicle (SULEV) standards. To completely meet the PZEV distinction, it must be a SULEV and have zero evaporative emissions from its fuel system and have a 15 year/150,000 mile warranty on its emission control components.
With Subaru PZEV vehicles, the remarkable reduction of smog-forming emissions is achieved through four key areas: the catalytic converters, fuel injectors, Engine Control Module (ECM), and dual-filtration air-intake system.
With traditional catalytic converters, there are two stages. The first stage contains platinum and rhodium that converts oxides of nitrogen into harmless nitrogen and oxygen. The second stage contains platinum and palladium that converts hydrocarbons and carbon monoxide into carbon dioxide and water vapor. The catalytic converter installed in PZEV Subaru vehicles combines these two stages into one stage with multiple layers. As a result, more precious metals are used and the contact area is effectively twice that of a traditional catalytic converter, producing more effective conversion of pollutants.
The fuel injectors on Subaru PZEVs close tighter than traditional conventional injectors to prevent evaporative emissions from fuel leakage into the intake manifold.
Engine Control Module (ECM)
Vehicle emissions are worse under cold start conditions. Subaru addresses this problem by altering the programming of the ECM to delay ignition timing, making exhaust gases hotter, which helps the catalytic converter heat up sooner, reducing emissions.
In a conventional vehicle, unburned gas fumes can escape through the engine’s air intake once the engine is shut off. To prevent this, Subaru PZEVs are equipped with a charcoal canister in the air intake that absorbs these evaporative hydrocarbon emissions.
A Subaru PZEV vehicle allows drivers to reduce their impact on the environment while sacrificing nothing by delivering a win-win combination of advantages that include no complicated technology, no alternative fuels required, safety, affordability, performance and immediate environmental benefits.