The mayor said it has a "stylish, swooshing exterior"
Final designs for London's "new Routemaster bus" have been unveiled.
The double-decker uses green technology to be 40% more efficient, it has two staircases and an open platform enabling people to "hop-on hop-off".
London Mayor Boris Johnson said the new bus for the capital would be "iconic" and "beautiful".
A spokesman for Transport for London hoped the bus, which has three doors to speed up boarding, would be in service in 2012.
A Transport for London spokesman said the bus would be 15% more fuel efficient than existing hybrid buses, and 40% more efficient than conventional diesel double deckers and much quieter on the streets.
It has a "glass swoop" at the back and "an asymmetric design for the front-end completes the futuristic look".
Routemasters could be back on the streets by 2012
Mr Johnson said: "This iconic new part of our transport system is not only beautiful, but also has a green heart beating beneath its stylish, swooshing exterior."
He added: "I expect to eventually have hundreds of these on London's roads, and for cities around the globe to be beside themselves with envy for our stunning red emblem of 21st Century London."
Peter Hendy, London's Transport commissioner, said: "Designing and building a new bus exclusively for London is an exciting project to be working on and one of which we are all proud.
"This beautifully designed, environmentally friendly vehicle built for the capital will be loved by Londoners for many years to come."
Stop and notice
Mark Nodder, group managing director of manufacturer Wrightbus, said: "I think the design is genuinely groundbreaking, people are really going to stop and notice these buses on the streets of London."
In December 2005 the original Routemaster was withdrawn from general service on accessibility and environmental grounds, but it is still used on two heritage routes in London.
In July 2008, a competition was launched by Mr Johnson to design a new Routemaster bus for the capital, attracting 700 entries.
Warwickshire-based sports car maker Aston Martin, along with architects Foster and Partners, won the £25,000 prize jointly with Wiltshire bus maker Capoco Design.
The contract to build the new bus for London was awarded to Wrightbus in January 2010.
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