Low Emission Vehicle, an intermediate California standard about twice as stringent as Tier 1. Ultra Low Emission Vehicle, a stronger California standard emphasizing very low HC emissions. Super Ultra Low Emission Vehicle, a California standard even tighter than ULEV including much lower NOx emissions and more durable control systems. Zero Emission Vehicle, a California standard prohibiting any tailpipe emissions. The levels of pollution permitted under each standard depend on the vehicle type.
Many light trucks have weaker standards than cars.
Each model's precise emissions standard is reflected in its Green Score and Class Ranking. The pollution coming from a vehicle depends on the standard it meets, how well its emissions controls work, how it is driven and maintained, fuel consumption, and fuel quality. Vans, pickup trucks, and sport utilities are classified by the government as light trucks, and so have less stringent emissions and fuel economy standards than passenger cars. As a result, and as our ratings indicate, the average light truck pollutes more than the average car. Some of the heaviest light trucks, such as large sport utilities, are exempt from light duty regulations, and are among the most polluting of personal vehicles.