The diesel-electric hybrid &34'New Bus for London,&34' made by Wrightbus and designed in conjunction with Heatherwick studio, has been chosen to be London&39's new bus.

London Mayor Boris Johnson unveiled new diesel-hybrid electric double-decker buses this week that are scheduled to hit London streets in 2012.

The new hybrid buses will get 10 miles per gallon which is almost 40 percent more efficient than a conventional diesel double-decker bus. London already has some diesel-hybrid buses in its fleet, but these newer models will be 15 percent more efficient than those.

"Over the next few months its mettle will be well and truly tested. But I hope that process will confirm we have built a real eco-warrior of a bus that can contribute to improving the air of our city, while transporting Londoners in great style and safety," Johnson said in a statement.

London will still be keeping its iconic double-decker chassis.

The chosen model, called the "New Bus for London," is made by Wrightbus and its design was done in collaboration with Heatherwick Studio.

While 10 miles to the gallon may not seem like much of an improvement, if every bus in London performed to that standard it would reduce London's bus fleet NOx emissions by 57 percent, and its CO2 emissions by 230,000 tonnes annually, according to the mayor's office.

The buses will be tested over the next few month, with plans to begin replacing London buses starting in 2012 under the operation of Arriva London, just in time for the London 2012 Olympics.

London is not the only city revamping its iconic transportation.

The New York City Taxi and Limousine Commission and Mayor Michael Bloomberg announced in early May that the plug-in hybrid Nissan NV200 minivan will be New York City's next taxi cab.