Accumulating carbon dioxide (CO2) in our atmosphere is a driving factor in global average temperature increases. There are well over 278 million personal and commercial vehicles in the US today. On average, each emits around 4.6 metric tons (tonnes) of CO2 annually. This means the US vehicle fleet emits at least 1.3 billion tonnes of CO2 every year and that doesn’t even include airplanes, trains, boats or small gas powered engines (lawn mowers etc).