Many Cars Pollute Less Despite Increases in Size

As new vehicles become more efficient, the amount of carbon dioxide (CO₂) they produce decreases. Shown below are several examples of model year (MY) 2012 cars that have decreased the amount of CO₂ they produce (in grams per mile) despite the fact that they are larger (in interior volume) than they were ten years ago. Of the examples, the Kia Optima had the largest decline in CO₂ emissions in the ten-year period, and the Nissan Sentra and VW Jetta had the greatest increase in interior volume while still reducing CO₂ emissions.