Traffic in Shanghai. Photo by SmokingPermitted.

A gloomy sunset on Beijing’s 5th Ring Road. Photo by Lim CK.

A gloomy sunset on Beijing’s 5th Ring Road. Photo by Lim CK.

Obama on wheels. Photo by Scorpions and Centaurs.

<

p>Poznan’s currently car-free central square is threatened by increasing traffic congestion in the city. Photo by Lee Schipper.

Photo by gisleh from Flickr.

A man making his own biodiesel. Photo by Mike Murrow from Flickr.

Are car companies thinking about more than one type of green? Photo by makeshiftlove from Flickr.

Bigger isn’t always better. Photo by powebooktrance.