I think this is once in a blue moon and only certain group will
choose. Most of the time, all cheapo pax will take the colorful one
except white and black and sometime silver.
Like that day, in the RWS, after queuing a while, I'm finally
the third in the queue and in front me is blue and the 1st one is
silver. 2 pax come and the cheapo well dressed lady pax (first pax)
immediately skip the first one and hop onto the blue. The next pax
puzzled and just hop on the silver. Imagine is just in the mid Sat
morning that pax also choose taxi.
But anyway does idling will cost more diesel? I put to neutral
will waiting and I though is ok? Not sure can someone enlight?
If can, put to parking, when in neutral, the engine is still
running with slight combustion with spark plug still firing, a lost
of fuel, only the gear is disengaged, ny putting into parking
position, the engine completely come into a stopping position,
lesser fuel injection and the spark plug stopped operation.
But because putting into parking hv to go all way up pass
reverse, most like to put to neutral which is fuel consuming.
Depend on the Q, if it is moving, then neutral is ok, if not,
then parking, if kenna stuck somewhere and have to wait for a
long one, off the engine lah 
