Jon Stewart:

Hybrid cars are good for the environment, right? Their ability to switch to battery power means more miles to the gallon, and lower greenhouse gas emissions.
 These things are true, however recent research suggests that precisely how green hybrid vehicles are may depend on traffic levels, road design and, perhaps most intriguingly, national driving styles. It also shows these vehicles provide significantly greater environmental benefits in cities in India and China, where there are hardly any hybrids, than they do in places like Tokyo and Los Angeles, where they are most common.
 While sitting in a traffic jam in India, Anand Gopal and his colleagues at the US Department of Energy’s Lawrence Berkeley National Laboratory began thinking about how much driving conditions vary from country to country. They decided to investigate real-world conditions and the performance of different systems that deliver power to vehicles.