neutral coasting?
10-01-2012, 05:44 PM
#1
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Vehicle: 2004 Elantra
neutral coasting?
I have a habit of tossing it into neutral when im slowing down >30ish mph or going downhill. Can this harm any part of the drivetrain? I searched and saw different opinions on the subject.
10-01-2012, 08:24 PM
#2
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I don't know how they programmed the 2004, but my car has a zero-fuel engine mode where >1700 or so RPM with closed throttle the computer cuts all gas and it coasts/engine brakes. You'll save gas in gear.
10-09-2012, 05:30 AM
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You'll save gas in gear.
Depends. If you're coasting to stop at a red light or something, sure. You'll use zero gas with Deceleration Fuel Cut Off. However, if you're looking to save gas over a period of miles, you'll use less fuel on average by coasting in neutral. To put it another way:
Decelerating with DCFO, in gear: You are removing X amount of energy from your car by converting kinetic energy into heat and noise.
Coasting in neutral: You are removing 0.1X energies due to heat and noise, and only using up 0.2X energies in fuel use.
To put it another way:
If you integrate the function of how much net energy (kinetic energy because it's moving, potential chemical energy stored in the fuel and battery) your car contains over time, there will be more area under the graph of a car accelerating then coasting in neutral, than there would be of a car accelerating then decelerating with DCFO.
I'm too lazy to do that in paint. Of course the next step for saving gas is to turn the engine off when you are coasting in neutral, then bump starting it when you are ready to accelerate again. 50 MPG don't come for free.
10-09-2012, 09:32 AM
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10-09-2012, 10:39 AM
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10-09-2012, 10:45 AM
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Doesn't have to be a hybrid. The semi delivery truck last here would shut down the motor when the parking brake was set after 15 seconds or so. UPS has been doing it for the last three or four years, don't know if it is automatic now or not through.
Start-stop engine technology coming to a car near you
Start-stop engine technology coming to a car near you
10-09-2012, 11:51 AM
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So I'm confused. Is it still better to coast in nuetral then? Except of coarse now your brakes take a slighter bigger load, wearing them quicker. Not sure if you want to calculate that into the equation...