I think the answer to diesels idling and clogging up their emissions is Compressed Natural Gas, or CNG. You are seeing more and more commercial fleets switching to it, such as garbage trucks, UPS and other delivery vehicles and trucking companies. Great idea which I hope translates to private vehicle use. Plenty of home grown supply and burns very clean. All that's needed is the infrastructure of filling stations across the country. I think they are coming as I see more and more local, Western New York companies switching over, the most recent being a beer distributer.