this topic has opened up a whole can of worms.
If you are coasting down hill in neutral to save fuel, YOU ARE USING MORE FUEL, FACT.
The engine has to use fuel to tick over in neutral,
it does not use any fuel if it is coasting in gear.
Another thing is, if you need to accelerate out of trouble all you do is stick your foot down on the loud pedal, and I would'nt advise going in and out of gear while travelling, clutch and gearbox are going to take a hammering.
I have owned a smart for four and a half years, so I feel qualified to answer

Ellis.
ps. so far after four and a half years, zero defects, just thought you would like to know about long term ownership, as you are all newbies to smarts.