Route 11, which runs between Liverpool Street Station and Fulham Broadway, will be converted to the new vehicles on Saturday 21 September with 25 of them running during peak hours.
Mayor Johnson said: “I am very pleased that we can announce that route 11 will be next to be served by these beautiful, bespoke, economy-boosting buses. They have world-leading environmental credentials and offer an unparalleled passenger experience.”
Transport for London claims the bus is the “greenest diesel electric hybrid bus in the world” although its green credentials have been questioned by critics and the Mayor recently admitted the bus would not comply with his own Ultra Low Emission Zone.
TfL has ordered 600 of the £354,500 vehicles which it will make available to bus operators and will also cover the cost of a second crew member needed to supervise use of the rear platform.
The total cost of buying the buses is expected to be £212m with a further £37m spent on the second crew member.
Darren Johnson, a Green party member of the London Assembly, said the costs “will add up to £80m onto the fares bill between now and 2016” and warned that “this is a huge sum of extra cash to find during years of austerity driven cuts in the Government’s grant to Transport for London.”
Assembly Member Johnson has also questioned the decision to develop a new hybrid bus and says TfL “should be buying cheaper existing hybrids now and preparing to make the switch to electric buses.”