All efficient driving manuals advise against driving in neutral, but mainly do so for security reasons. There are ways to save based on this technique, if done well. Some automatic transmissions also save so without losing security.
Gerhard Plattner, efficient driving expert, a real crash. If you want to be like him, read on ...
All engines electronic injection (100% of what is sold today) do not consume any fuel if there is in gear and the throttle is lifted. Unless there is a risk of draft by low revs, electronics understands that the wheels move the motor via transmission, and no need to consume.
However, consumption is 0, but it is decelerated, is the engine brake. It is the best way to stop, of course, but there are situations that we are not interested, because it would be counterproductive to lose speed having to win later. Knows that a skilled driver, and that there is a room for improvement performance.
There are security issues associated with driving with neutral, because the brake booster is less effective if we need it, and lost control of the car withholding. But in conditions of high security, circular neutral It is not stupid if certain conditions are met.
Today we have some automatics that decouple the engine from the transmission (work in neutral) when not accelerated. For example, do the DSG / S tronic boxes VAG Group when we have extra to select automatic mode, economical and dynamic driving. In economy mode, the box makes this feature.
If it is detected that the driver is braking frequently, the ECU understands that we want to continue keeping packed, and the engine is idling. This means a consumption of 1 liter / hour or less, depending on the electrical consumers (and use), engine and other conditions. No problem for safety.
As soon as the brake pedal is touched, a gear is engaged, so there is no risk of loss of control. Consumption can be improved, and improved, especially on routes with little slope, which do not stop missing. If we do that gear is engaged, we enlenteceremos before, or we will have to inject more fuel per hour idling.
As soon as the accelerator pedal, the engine control unit revolutionizes the march insert the correct regime and not notice any hitch, and in a very short time. This is the kind of behavior that should follow the skilled driver with manual transmission, safety first, after saving.
The less retain the engine without accelerating, the technique is less effective. Engines are less retained logically the smaller displacement, have less mechanical friction and pumping losses under air to the cylinders. The higher the displacement, the greater the benefit, is not the same do this in a 1.0 to a 2.5.
It will be noticed more on petrol engines
Moreover, also imported the marches. The longer (less engine revs for the same rate) lower retention in sixth always have less back pressure than fourth. The fewer gears have the car, the greater the potential benefit, because there very long marches.
In cars like the SEAT León Ecomotive, this technique only will we save fuel: engine displacement and with very little long marches
If we add what has been said, we see that the ideal car to implement this technique has a displacement shooting high, few marches and cortitas. If we talk about carbureted cars, which do not cut the fuel injection, neutral technique makes more sense yet. If you do not have a good old classic, the safer your car is electronic injection.
It's very important memory know revolutions to which we must go. For example, if we go to 80 km / h in fifth and put standstill, the engine drops to 800-900 RPM. If we want to get fifth, we must accelerate the engine a bit, up to 2,500 RPM (eye, is an example), before releasing the clutch. If we do not do well, we crush clutch and long-term damage that is expensive.
This technique requires maximum concentration by the driver, because it must always be prepared to insert a gear, you play. It is not advisable to do this with heavy traffic or winding roads or in urban areas. On the contrary, it is best done in places that we know very well, to what amount and what sections descend. So we get a slight savings, and we will not put our safety.
Regarding the electric cars, This technique has the advantage of not consume energy, but not lose speed regenerate. The effect will be much the same if you step on the accelerator just enough to stop energy recovery and in turn, the power consumption is zero. It needs to be fine with the right pedal.
In the hybrid cars, This technique makes sense in specific models. For example, in the case of Toyota and Lexus, we are interested below 80 km / h, because we can pack the car faster without forcing the gasoline engine to engage the transmission (occurs and to protect the electric motor ). This is already splitting hairs, saving is very small, so much that carry electronics.
Never turn off the engine in neutral, never!
In the not too distant future, as we forward a patent Bosch, the engine will shut off instead of idling and running. Everything is automatic. Turn off the engine in a conventional car for driving in neutral is quite dangerous, and this really what one should not do, but run the risk of running out of fuel from one moment to another.
It is best to call the crane to gamble, the risk of losing the power steering runs, the brake booster, and even the functioning of the airbags, Do not even think!