2009 Subaru Legacy Wagon PZEV
2009 Subaru Legacy Wagon PZEV . Click image to enlarge

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By Jim Kerr; photos by Jil McIntosh

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2009 Subaru Legacy PZEV

There are many acronyms used when automobile manufacturers start talking about emissions levels. LEVs, or Low Emission Vehicles, are making way for ULEV (Ultra LEV) and even SULEV (Super Ultra LEV). The ultimate in low emissions is a ZEV, Zero Emissions Vehicle, of which really only electric vehicles fit this category.

However, some critics say that electric vehicles only change the source of the emissions to the electricity-generating power plant instead of the vehicle. Very close to ZEV in emissions levels, but without needing to be plugged in, are PZEV, or Partial Zero Emissions Vehicle. They offer the best rating possible for a gasoline powered vehicle and may be what many vehicles will be like in the future.

But you don’t have to wait to drive one. Subaru is selling PZEV vehicles right now. Subaru’s 2009 Legacy and Outback are available as PZEV models and amazingly, these cars are 90% cleaner than an average new car and even cleaner than current hybrid technology. To meet the PZEV standards, a vehicle must meet the SULEV standards for tailpipe emissions and the ZEV standards for evaporative emissions.

2009 Subaru Legacy Wagon PZEV
2009 Subaru Legacy Wagon PZEV . Click image to enlarge

Subaru does this by combining special engine computer programming with some additional hardware to eliminate or reduce emissions. This can be done inexpensively compared to the technology costs of a hybrid vehicle or the new low-emission diesel systems. Customers get a vehicle that operates and feels like their existing gasoline vehicle and they don’t have to worry about finding diesel fuel stops or the cost of replacement batteries in the future.

To meet the PZEV standards, Subaru had to deal with both exhaust and evaporative emissions. Controlling exhaust emissions is done by increasing catalytic converter efficiency. Most vehicles use one catalytic converter (some V-style engines use two) but all Subaru PZEV models use two converters for more capacity. The converters have reduction stages, which break the harmful emission gases apart, and oxidization stages, which combine those gases into non-harmful gas combinations. Precious metals such as Platinum, Palladium and Rhodium are used in the converter to make this process happen and the Subaru converter design places the reduction and oxidization stages in layers which allows them to use more precious metals in the same space and effectively double the effectiveness of the chemical reactions.

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