The EPA has rolled out a new campaign explaining the rating system and encouraging consumers to look for the SmartWay leaf logo on new and used SmartWay-certified vehicles. The EPA estimates 20 percent of all vehicles qualify to be certified.
In its Green Vehicle Guide, which covers vehicles released since 2000, the EPA gives vehicles two scores based on air pollution and greenhouse gas emissions, each on a one-10 scale.
The air pollution score looks at a vehicle's tailpipe emissions, and a score of 10 means a vehicle emits no pollutants that contribute to smog or health issues.
The greenhouse gas score is based on carbon dioxide, nitrous oxide and methane emissions, and is tied to a vehicle's fuel economy. The better the fuel economy, the higher the score. The rating also takes into account a fuel's lifecycle, including production, refining, distribution and use.
To be SmartWay certified, a vehicle must earn a six or higher for each score and have a total score of at least 13. A special SmartWay Elite designation is given to vehicles that earn a nine or 10 for each score.