This is not the article I read originally which was for a gasoline-powered auto, but it shows great advances have been made. It mentions cleaner tailpipe than ambient air (this one on natural gas).
The Cleanest Cars on Earth?: Honda Civic GX and Other Natural Gas Vehicles (NGVs) - Gas 2
After this period more advances have been made. From Honda:
"The gasoline-powered Honda Civic is an Ultra-Low-Emission Vehicle. In 2000, an Accord became the first gasoline-powered car sold in California to meet the Super-Ultra-Low Emission Vehicle standard. Two years later, Honda introduced a new generation of gasoline engines around the world, with extremely low emission levels and increased fuel efficiency that also helped improve driving performance."
Thor Forums
