Coasting in neutral, good idea or bad?

tinkerbell84

you can't 'coast' in gear. by definition it's being in neutral!

Hintza

If you follow the example set in some parts of Africa where they will turn off the engine on downhill sections and switch off the lights when they think they know the road. A taxi will carry upto 26 people and when it goes horribly wrong which it does do frequently the loss of life can be horrific.

Drive in control of the vehicle at all times.

Idiophreak

PinchyPenny wrote: »

I noticed that when driving downhill, the car rev counter would stay around 2000 rpm as I went, my foot off the accelerator pedal in top gear. Going down the same hill and placing the car in neutral I can coast along, sometimes faster, and the revs go down to around 900rpm.

As has been said, the 900rpm is caused by the engine burning fuel to tick over.

The 2000rpm is caused by the wheels turning the engine.

Coasting out of gear will use more fuel than "coasting" in gear.

Inactive

tinkerbell84 wrote: »

you can't 'coast' in gear. by definition it's being in neutral!

Surely if you disengage the clutch whilst in gear, you can " coast " in gear.

Idiophreak

Inactive wrote: »

Surely if you disengage the clutch whilst in gear, you can " coast " in gear.

If you disengage the clutch, you aren't "in gear"??

Pew_Pew_Pew_Lasers!

If the clutch is disengaged the vehicle is not in gear.

tinkerbell84

Idiophreak wrote: »

If you disengage the clutch, you aren't "in gear"??

you beat me to it!!!!

pault123

Inactive wrote: »

Surely if you disengage the clutch whilst in gear, you can " coast " in gear.

Keeping your foot pressed down on the clutch pedal and leaving gearstick in gear or taking it out of gear for that matter is the same - the clutch disengages the flywheel.

Comparing neutral gear vs foot pressing the clutch on a downhill in theory is the same thing, but in reality the foot pressing the clutch will cause wear on the clutch bearings.

If your going to coast its better to do it with no foot on the clutch in no gear. Although less/no fuel is used if you can pick the right gear to keep yourself rolling down the hill without any revs - and control of the car maintained to boot.

pault123

Inactive have a look here, the first pic shows what happens when the clutch is pressed, the fly wheel and clutch plate disengage,


http://www.dorwey.co.uk/clutch.htm

Wig

Idiophreak wrote: »

As has been said, the 900rpm is caused by the engine burning fuel to tick over.

The 2000rpm is caused by the wheels turning the engine.

Coasting out of gear will use more fuel than "coasting" in gear.

It would help if someone with an mpg display could test this theory on a suitably long downhill section. The difference of course would be that if the hill is not sufficiently steep the car in gear is going to slow down significantly and will probaly require some accellerator pedal to keep it going. A car rolling along with only wind resistance is likely to go much further.

So IMHO the 'rolling' car is on the whole likely to save more fuel than the 'in gear' car. And if you feel confident doing it (as I do) then do it.