Bikes & Cars...

I was just in Buenos Aires, Argentina, enjoying long, sunny, Southern-Hemispheric days — and choking on clouds of stinky, old-fashioned diesel. While the U.S. market has diesels you can stand behind while wearing a white linen suit and not get dirty, Baires drivers still use the smelly, sooty, decidedly non-green diesel in cars, trucks, and city buses.

Compounding the massive carbon footprint left by all these old-skool engines is the rotten...