How sure? I won't correct you but that's really a gamble too
much. (I wonder what you will do if SMRT orders more
bendies 
)
Anyway, I don't mind DDs on SMRT, as long as they still remain
useful 
Don't want to come back to another stupid debate, so
yeah. 
Gamble? I won't hope much, given their state of their operations
right now. I would certainly discourage SMRT to do so (buy new
bendies) if they wants to be more efficient which they have to
in line with the new BSEP.
If you do not know what you're talking about, please do not make
such assumptions.
In practise, there is a lot that can affect the performance and
fuel economy of a city bus (e.g. weight / load, topography, engine
design, maintenance, driver training / driving style). There
is a very important relationship between the engine and the
transmission that affects the engine speed at any given road
speed. It is therefore perfectly possible for bus with a
small displacement engine to use more fuel than a bus fitted with a
large displacement engine simply because it is working at
non-optimal engine speeds when cruising at important road
speeds.
You sound like a typical 'fleet manager' who has never been
involved with buses or understand the relationship of power and
torque outputs of an engine vs. displacement.
Yes, it is perfectly possible for a small displacement engine to
make similar peak power and torque figures compared to a large
displacement engine, but at what cost? You need a larger
turbocharger capable of supplying higher boost pressure to the
engine (read: slower transient throttle response and higher boost
threshold), larger cooling system to handle the increased heat
rejection, stronger internal engine components in order to cope
with the higher operating pressure, and possibly shorter servicing
intervals due to the engine operating at closer to its physical
limitations. Furthermore, a small displacement engine
produces low torque at the most important low engine speeds where
the turbocharger is inefficient, which is not ideal for
driveability, meaning that in order for the bus to accelerate at a
sufficient rate, you need to keep the engine speeds high which in
turn means unnecessary noise and vibration. Larger engines
not only produce high power and torque at lower engine speeds, but
also provide a larger torque band - a window of engine speeds where
peak torque is available under foot. This ensures less
gearchanges required even in harsh topographies and the possibility
of using a taller final drive ratio, further keeping engines speeds
and therefore noise and vibration levels lower.
So in short, smaller engines DO NOT automatically mean lower
fuel consumption.
Thanks for the info. 
I may not be a tech guru in engines but in today's automobile
industry, many auto manufacturers are downsizing car engines while
producing adequate power to propel the car. In fact, due to motors
integrating with electrical hybrid designs and turbochargers, the
future is about such technologies, while maintaining low fuel
consumptions and keep it small.
As for our road tax structure, it simply discourage our
operators to buy big engine capacity buses. Thus looking into
smaller engines that provides acceptable performance while going in
line with the government green policies.
