Data was collected from more than 68,000 vehicles in Denver, Tulsa, and Los Angeles. According to the researchers, “Using fleet fractions from previous data sets, we estimated age-adjusted mean emissions increases for the 2013 fleet to be 17–29% higher for carbon monoxide, 9–14% higher for hydrocarbons, 27–30% higher for nitric oxide, and 7–16% higher for ammonia emissions than if historical fleet turnover rates had prevailed.”
Despite tough economic times, sales of Nissan LEAFs and Chevy Volts has remained strong, although still representing a small portion of auto sales nationwide.