A low emission vehicle (LEV) is a vehicle that emits significantly less pollution as a by-product of its engine operation when compared to similar vehicles. The term is used generally to describe any such vehicle, but is also a specific designation of an emissions standard introduced by the state of California in the United States. The California LEV standard was introduced in 1994 and expired in 2003, replaced by the LEV II standard. These standards set legal definitions for what qualifies as a low emission vehicle according to the amounts of pollutants found in the engine exhaust. A third level, LEV III is proposed for 2014.
Reduced emission vehicles fall under several categories, of which a low emission vehicle is the least stringent. Vehicles with even lower emissions can qualify as ultra or super ultra low emission vehicles, and each standard has a set definition. The original low emission vehicle standard also has different specifications according to vehicle type as well. The standards for a heavy cargo truck, for example, are different than for a passenger car. Diesel and gasoline engines, however, are judged on an equal basis.
Vehicle emissions for the LEV standard are measured in grams per mile, which may seem like an odd system at first, but provides a baseline allowing any vehicle to be compared fairly against any other. Emissions components regulated by LEV standards include all non-methane organic gases, all nitrogen oxides, formaldehyde, carbon monoxide, and particulates. Allowable levels were set slightly higher for vehicles with higher mileage or age. For a low emission vehicle with less than 50,000 miles or less than five years old, for example, carbon monoxide emissions could not be more than 3.4 grams per mile.
The second tier of LEV standards, LEV II, which was introduced for model year 2004 vehicles, changed the way certain vehicles were classified. This change in classification was made to reflect the increased usage of light duty trucks and sport utility vehicles (SUVs) as passenger vehicles. For the LEV II standard, these vehicles had to conform to the same standards as passenger cars. The difference between the two standards is significant, but not the same for every category of pollutant. For example, the same passenger car allowed 3.4 grams per mile of carbon monoxide emissions under the LEV standard is still allowed the same amount of this emission, but only 0.05 grams per mile of all nitrogen oxides as compared to 0.4 grams per mile under the original LEV standard.
The standards for low emission vehicle definitions can vary from country to country and even within states in the United States. California's standards, however, have, to an extent, become the industry standard, as they are some of the toughest standards in the world, and vehicle manufacturers that wish to sell vehicles in what is a very large and lucrative market must conform to them. This may change at some time in the future as other governments begin to enact their own standards, one of which could supplant the California standard as the benchmark for the auto industry.