Does coasting in neutral gear save petrol? and, is it dangerous?
Ive debated with many people about this, I think it saves petrol because the rpm is much lower, therefore less petrol is being drawn into the engine. I often put my automatic into neutral when coasting down hills or towards red traffic lights. Ive searched the internet about this and all ive found is this:
"12. Don’t coast in neutral
Coasting in neutral could save you money with old cars fitted with carburettors, but modern fuel injection systems cut the fuel supply off altogether as you slow to a stop, saving a surprising amount, especially in stop/start driving. And coasting in neutral, or with the clutch depressed, is potentially dangerous too, because you have no engine braking, and can’t suddenly accelerate out of danger."
How can the engine still be running if there is no petrol being used? And I cant think of any scenarios where being in neutral would be dangerous.
I dont know too much about mechanics, can anyone shed some light on this subject?
You’re in neutral and something bolts in front of the car. You instinctively push down the pedal so you can scoot out of the way. The engine roars but you go no faster because you are in neutral. So you get into an accident instead of driving around. In some states I believe it is actually a ticket-giving offense as they can claim you are not in control of the vehicle. How they could prove that is another story.
The engine still sucks in fuel as it needs to run. IF it saves any fuel the amount would be mere atoms not gallons.
You’re in neutral and something bolts in front of the car. You instinctively push down the pedal so you can scoot out of the way. The engine roars but you go no faster because you are in neutral. So you get into an accident instead of driving around. In some states I believe it is actually a ticket-giving offense as they can claim you are not in control of the vehicle. How they could prove that is another story.
The engine still sucks in fuel as it needs to run. IF it saves any fuel the amount would be mere atoms not gallons.
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If you are in neutral and need to quickly accelerate, you will need to remember to put the transmission back into gear, wait for the transmission to sync up with the speed your wheels are moving and then hit the gas. You are also putting more wear and tear on the transmission shifting into and out of gear.
I think you may be saving some gas but in the long run the safety and maintenance aren’t worth it, in my opinion.
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"Coasting in neutral could save you money with old cars fitted with carburettors, but modern fuel injection systems cut the fuel supply off altogether as you slow to a stop, saving a surprising amount, especially in stop/start driving." True, modern fuel injected cars cut the fuel off and the momentum keeps the engine running.
"And coasting in neutral, or with the clutch depressed, is potentially dangerous too, because you have no engine braking"
More contentious. Depends on the situation. Going down a steep hill in neutral is a bad idea whereas coasting up to a set of traffic lights is fairly safe.
"and can’t suddenly accelerate out of danger."
Apart from unwittingly getting caught up in Sergeant John Bunnel (rtd)’s Wildest Police Videos I can’t imagine where the need to suddenly accelerate out of danger might occur if you are driving sensibly.
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Hi,
While costing in neutral, although your foot is of the accelerator, the engine continues to run at its minimum speed (idle rpm) where a predetermined amount of fuel is constanty supplied by the fuel injection system.
The concenr regarding safety is real – when you are coasting in neutral the engine is disonnected from the wheels and if you need to come to a stop you are toally dependand on the brakes. At slower speeds this is not so much of a problem – but if you are costing at lets say 50 miles – you will find it hard to bring the car to a stop in a hurry, as opposed to being engaged in a gear and trying to decelerate from the same speed to a complete stop. You also increase the chances of locking up your wheels when you brake hard in neutral, unless you vehicle has abs.
Engine braking – this is when the engine is running slower than the wheels ( typically happens when you shift to a lower gear and suddenly release the clutch in a stick shift OR while you shift to a lower gear going downhill & release the clutch without stepping on the accelerator – you find the car slowing down although you have not hit the brakes) – this is engine braking.
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you really cant do this on modern cars,it can cause you to loose control as well as have a crash ,by cutting the engine your loosing your braking power as well as your steering and if something happened that you needed to speed up or slow down really fast ,your ability to do this would greatly be reduced,its not a good idea,your not going to save 3 cents worth of gas by doing this ,but you will be a danger to those in front of you,or around you if you loose control of the vehicle,and coasting with it running and in neutral doesn’t really help it either,good luck.
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been a certified mechanic for 37 yrs.
no
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SAVE GAS BUT IS VERY DANGEROUS AND IT IS ILLEGAL IN MOST STATES.
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923
Automatic transmissions are never meant to be coasting or cruising on neutral above 50 km/hr. For it will split the gears. Automatic transmission on AWD vehicle must never be placed on neutral even when coasting or cruising at 5 km/hr for it will surely destroy the differentials and the transmission gears.
Definitely you will save petrol for you will end up walking if you continue with this kind of driving. Not to mention it is quite dangerous for you will be more prone to accident. When in gear upon releasing the accelerator pedal can you feel a sudden deceleration? That is engine brake and that few seconds could save someone else’s life if not yours. And another thing you will not be saving hundreds of thousands of dollars on petrol by cruising on neutral. Try not to be a miser on life and death situations, that is if you do not care on spending for a replacement gear for your transmission.
Better be safe (though a bit expensive, I know) than sorry.
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In every state in the US coasting is illegal.
yes, it would save fuel…not as much as coasting with engine off- also illegal.
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