Some background info, BYD is a chinese automotive company that
builds mainly electric vehicles and Warren Buffet currently has a
10% stake in it.
The K9, when in a full low floor configuration, stores its
batteries ontop of the wheel arches and weighs only 6 tons
(compared to 11ton which other full sized 12m buses typically
weigh) and propulsion is fully achieved by 4 hub motors located on
each of the wheels.
Retail price of this in RMB is approx 2-3 million, which is
about 380k- 570k sgd as of today (which means smrt has been ripped
off). Range is about 250km, and takes 6 hours to recharge its
batteries to full or 30mins for a fast recharge to 50%.
http://chinaautoweb.com/2011/03/byd-k9-electric-bus-to-be-tested-in-denmark/ for
some photos.
Oh, and if u are wondering how does this thing sound when its
moving, just think of the LRTs. 
