Thanks mate,SlipStream said:It would save fuel, yeh, but more so if you made it a part of your greater driving habits. i.e. when the lights are red or you're coming to a stop, instead of shifting to lower gears to slow you down, just put the clutch in and glide... the RTA still reckon you should change down gears as you slow down - to help the engine slow you down - but why bother, unless your brakes are poo or they don't work at all...
So it would save fuel if you incorporated it into a smoother style of driving - accelerate smooth, change gears at a lower rpm, even when cruising down the main road, just put it into a gear that is normally too high (just to cruise along) - and then shift out when you need the power.
Having windows and stuff open increases drag - but only marginally. It's the same argument with roof racks - it might use an extra litre of juice for every 1000km of highway driving. Why don't we just fold the side mirrors in, cos they cause drag as well? Preference, basically. But it's just people picking nits. You could also fit skinner tyres to reduce rolling drag as well, while we're at it... who needs to turn??
I usually coast in neutral down hills and approaching red lights - but I don't have a stick shift so I can't choose a high gear from stationary. (It's a slow accelerating '73 Benz SE280)