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Old 02-21-2004, 08:18 PM   #1
therealrameth
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Question Driving in Neutral

Hello,
I drive an automatic 95 Toyota Corrolla. I drive a lot on roads with many traffic lights. Would I get noticable better gas milage if i put the car on neutral whenever I am not pushing the gas? For example, if there is a red light pretty far ahead, can i put the car in neutral and let it coast until the light and put it back on drive when the light goes green? What about on a downhill road where i dont need to press the gas?
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Old 02-22-2004, 01:35 AM   #2
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Quote:
Originally Posted by therealrameth
Hello,
I drive an automatic 95 Toyota Corrolla. I drive a lot on roads with many traffic lights. Would I get noticable better gas milage if i put the car on neutral whenever I am not pushing the gas? For example, if there is a red light pretty far ahead, can i put the car in neutral and let it coast until the light and put it back on drive when the light goes green? What about on a downhill road where i dont need to press the gas?


when going downhill I think it might save a very small amount of fuel (depending on the hill size of course). But on the actual road, I think it would only help you **** up your transmission. What say you VWhobo?
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Old 02-22-2004, 03:38 AM   #3
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though im not vwhobo, i think it might save on a little bit of gas, because you'll be running at a lower RPM (idle) if your not pressing the gas, compared to when you're driving, the RPMs will be up a little higher, so itle probably save some gass, probably not to much of a noticable amount. and i dont think it will hurt the tranny to much if anything
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Old 02-22-2004, 05:09 AM   #4
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Originally Posted by mazda6man
though im not vwhobo, i think it might save on a little bit of gas, because you'll be running at a lower RPM (idle) if your not pressing the gas, compared to when you're driving, the RPMs will be up a little higher, so itle probably save some gass, probably not to much of a noticable amount. and i dont think it will hurt the tranny to much if anything


well, if he throws it into nuetral because he sees a red light ahead and starts coasting to the light, and then when he's rolling the light turns green, he's going to have to shift back into drive. If the RPMs are up more than idle, over time, it will eventually wear the transmission down too much and it won't be able to take it. I'm just throwing out my opinion and what I think is right. just my
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Old 02-22-2004, 05:10 AM   #5
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You may save a very little amount of gas over time but there are two drawbacks, the constant N-D D-N shifting will equal increased wear, maybe slight but still... the other big factor I see is safety. I drive all day in city traffic and at least a time or two a day someone pulls in front of me at the last second, starts to merge without looking... you need to be in control of your car INSTANTLY, not waiting a second or two for the trans to engage.
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Old 02-24-2004, 05:03 PM   #6
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neutral engagment

You all are not very versed in automatic transmissions. One of the worst things you can do to an auto trans is to disengage it from drive range and re-engage while still moving. Based on fluid dynamics, valve body pressures and solenoids you are adding much un-needed wear to the transmission.

On top of the mechanical side of it, ANY-time you disengage the engine from the drivetrain of a vehicle while moving at a good rate of speed, your stability and control of the vehicle is compromised. It is a fact that physics and various law of perpetual motion can explain to you. Why in the world are you contemplating doing this? Are you so financially in the hole that ten cents in gas will determine if you eat tonight or not? God help you, that being the case!

If you actually think about it, in cars that have an automatic transmission, and at speeds where (if equipped) you are not going fast enough to have the "lock-up" torque converter in lock-up, letting off the gas completely will slow the engine back down to idle or close to idle just the same as letting off the gas with the transmission still engaged in range "D." That is what a torque converter does, it allows a fluid coupling between the engine and transmission such that when you are not accelerating, you are breaking that direct connection between engine and driveline. It just does it such that the connection is not "hard-broken" (IE...shifter in neutral and totally disconnected) and when you accelerate, it is ready to engage based on fluid pressure, fluid dynamics and thermodynamics.

In a manual transmission I see no real wear issues with doing this ONLY if your vehicle is built so that the transmission is being lubricated when in neutral and in motion. Some are not, hence, neutral combined with motion is not a good thing. I argue that in the absence of the above, you are far more likely to lose stability and control of a manual with it in neutral and coasting down the road than in an automatic in the same situation. You all may think that premise sounds crazy, but think of it like this. A vehicle in motion is a combination of many things all encompassing mechanical balance. When a vehicle, be it manual or auto is in motion, the engine and driveline need to be connected because that is the way they were built to be operated. Gas consumption is a mute point as well as totally negligible.
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Old 02-24-2004, 05:29 PM   #7
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Quote:
Originally Posted by cmeseadoin
You all are not very versed in automatic transmissions. One of the worst things you can do to an auto trans is to disengage it from drive range and re-engage while still moving. Based on fluid dynamics, valve body pressures and solenoids you are adding much un-needed wear to the transmission.

On top of the mechanical side of it, ANY-time you disengage the engine from the drivetrain of a vehicle while moving at a good rate of speed, your stability and control of the vehicle is compromised. It is a fact that physics and various law of perpetual motion can explain to you. Why in the world are you contemplating doing this? Are you so financially in the hole that ten cents in gas will determine if you eat tonight or not? God help you, that being the case!

If you actually think about it, in cars that have an automatic transmission, and at speeds where (if equipped) you are not going fast enough to have the "lock-up" torque converter in lock-up, letting off the gas completely will slow the engine back down to idle or close to idle just the same as letting off the gas with the transmission still engaged in range "D." That is what a torque converter does, it allows a fluid coupling between the engine and transmission such that when you are not accelerating, you are breaking that direct connection between engine and driveline. It just does it such that the connection is not "hard-broken" (IE...shifter in neutral and totally disconnected) and when you accelerate, it is ready to engage based on fluid pressure, fluid dynamics and thermodynamics.

In a manual transmission I see no real wear issues with doing this ONLY if your vehicle is built so that the transmission is being lubricated when in neutral and in motion. Some are not, hence, neutral combined with motion is not a good thing. I argue that in the absence of the above, you are far more likely to lose stability and control of a manual with it in neutral and coasting down the road than in an automatic in the same situation. You all may think that premise sounds crazy, but think of it like this. A vehicle in motion is a combination of many things all encompassing mechanical balance. When a vehicle, be it manual or auto is in motion, the engine and driveline need to be connected because that is the way they were built to be operated. Gas consumption is a mute point as well as totally negligible.
I'm in full agreement with that, you must NEVER EVER put any car, man or auto into neutral whislt driving as it messes with the transmission. That's why you a recovery man etc will never tow an auto car with the driven wheels on the road surface (dif.lock etc)! Also, from the safety point of view it is dangerous to coast in any vehicle because when driven, the wheels act with you to control the car (the engine acts as a brake on a car) and with no power going to them the car will just gain speed continuously deeming it harder to brake! as for the MPG, I doubt it saves any fuel at all, infact it probably uses more!
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Old 02-24-2004, 05:56 PM   #8
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Quote:
Originally Posted by Cliffy
...and with no power going to them the car will just gain speed continuously deeming it harder to brake!

Is that on the uphill slopes and the flat ground?

Maybe it's just me, but when I put my car into neutral (5spd) it starts to slow down...could just be the thick air here in So. Cal.
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Old 02-24-2004, 06:28 PM   #9
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Quote:
Originally Posted by therealrameth
Hello,
I drive an automatic 95 Toyota Corrolla. I drive a lot on roads with many traffic lights. Would I get noticable better gas milage if i put the car on neutral whenever I am not pushing the gas? For example, if there is a red light pretty far ahead, can i put the car in neutral and let it coast until the light and put it back on drive when the light goes green? What about on a downhill road where i dont need to press the gas?
Hey Bav, who said anything about coasting up hills lol....do you guys in the States have uneven road surfaces or is it just us here in Sunny England!
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Old 02-24-2004, 06:40 PM   #10
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Quote:
Originally Posted by Cliffy
Hey Bav, who said anything about coasting up hills lol....do you guys in the States have uneven road surfaces or is it just us here in Sunny England!

Uneven road surfaces? Explain an uneven road surface. Engineering a road can have its ups and downs...as the terrain goes and as is feasible. It is sometimes more cost effective to leave the whoop-dee-doo's in. The problem in England is that pavement has a nap to it...it lays one way. You are all driving against the nap and so this causes more problematic pavement.
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Old 02-24-2004, 06:50 PM   #11
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Uneven road surfaces? Explain an uneven road surface. Engineering a road can have its ups and downs...as the terrain goes and as is feasible. It is sometimes more cost effective to leave the whoop-dee-doo's in. The problem in England is that pavement has a nap to it...it lays one way. You are all driving against the nap and so this causes more problematic pavement.
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You mean a camber? If you do then IMHO it's more logical for guttering reasons! but by uneven I meant ups and downs eg; slight inclines
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Old 02-24-2004, 06:57 PM   #12
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You mean a camber? If you do then IMHO it's more logical for guttering reasons! but by uneven I meant ups and downs eg; slight inclines

No. The "nap" thing was a joke.
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Old 02-24-2004, 07:08 PM   #13
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No. The "nap" thing was a joke.
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Sorry Bav...call me a pratt, tosser...Fic Brit bloke, what evr, but I dont get it lol
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Old 02-24-2004, 07:16 PM   #14
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Sorry Bav...call me a pratt, tosser...Fic Brit bloke, what evr, but I dont get it lol

Isn't it the English (among others) that drive on the "opposite" side of the road?

There is no "nap" to asphalt pavement, per se. But if there was and since England drives on the wrong side of the road...that would be driving against the nap (or grain) of the asphalt and thus cause ripples and uneven-ness.

I don't like having to explain jokes...but it could possibly be that it was only funny in my head.
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Old 02-24-2004, 07:24 PM   #15
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Isn't it the English (among others) that drive on the "opposite" side of the road?

There is no "nap" to asphalt pavement, per se. But if there was and since England drives on the wrong side of the road...that would be driving against the nap (or grain) of the asphalt and thus cause ripples and uneven-ness.

I don't like having to explain jokes...but it could possibly be that it was only funny in my head.
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lol, I understand fully now and it was probably only funny to you
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