Originally posted by free4ever:
If you car breaks down, try pushing the car wit the gears in P or
D, the car probaby will not move. N is also useful here.
I totally agree with you on that point, it could happen
when you want to push your car when you run out of fuel for
instance hehehe 
And one more thing, shifting frequently will
cause wear and tear but that does not mean shifting into N will do
damage the gearbox. Example when you are waiting for someone,
shifting to N might be a good idea.

I think I would rather off my engine than keeping it
idling for some time. The manual I read strongly against engine
idling. Idiling is only for coldstarting the car
only...
Anyway thank you for the various input so far... It has really been
wonderful knowing about it... 