Does non-moving A/T car consume more fuel if...

[ghosthunter]

Does a non-moving A/T car consume more fuel if the shifter is in D or N ??

Imagine the situation is you are waiting for the traffic light to change from red to green.

[alwayz_yummy]

D consumes more kasi engaged ang tranny and braking it counter-acts the action of the tranny--kaya nga bumabagsak yung idle speed ng engine...

N- is just in neutral--free moving ang a/t...

eto pagkakaintindi ko..

[ess]

How about for short stops (e.g. less than 1 minute)?
Will transitioning from D-to-N then N-to-D for short stops consume more fuel than just sticking to D?

[redorange]

Whatever fuel you conserve won't be worth the cost of a new tranny caused by the wear and tear you cause from shifting back and forth for short stops. The rpm variation between D and N is really negligible to matter, you'd save more fuel by driving smart.

[alwayz_yummy]

kung madali lang ang traffic light, say less than 30 secs--leave to d lang..pero kung jam na iba na usapan yan...

ang mahirap is ung filipino-traffic situation called: tutukan--where in ayaw mo pasingit sa mga pilit na sumisingit..

[XTO]

D is my vote. not only gas consumption but also brakes and battery.

[ptk675]

kung quick stops lang, say a minute or less, ok lang iwan sa D. Pero kung matagal na stops, i think its better to put it in P.

Not sure how true it is but I read somewhere that leaving an AT tranny in the N position for extended periods will starve the tranny of ATF.

[ronw123w124]

I would be more concerned about the stress you put on a transmission by leaving it in "D" position in a traffic jam, because it is engaged in "D" and it is suppose to be moving, IMO, it is better to shift to "N" when the car is in standby mode.

[1D4LV]

I would be more concerned about the stress you put on a transmission by leaving it in "D" position in a traffic jam, because it is engaged in "D" and it is suppose to be moving, IMO, it is better to shift to "N" when the car is in standby mode.

+1 here. even though the stops are quite low like let's say, 30 seconds, it is still moving, so the load is on the transmission as well as on the brakes.

it is better if even in short stops, that you put it in neutral. you save gas, you save your brakes, you save your transmission. and besides, i think modern AT assemblies are very durable to do that.all it takes is one click of your hand.

[Lucius]

+1 here. even though the stops are quite low like let's say, 30 seconds, it is still moving, so the load is on the transmission as well as on the brakes.

it is better if even in short stops, that you put it in neutral. you save gas, you save your brakes, you save your transmission. and besides, i think modern AT assemblies are very durable to do that.all it takes is one click of your hand.

Good one. On my mazda3, when I keep it on D then i pull up the hand brakes, it advances pa din. Mas ok kung naka N na lang, ganun din naman. Unless gusto mo ng full throttle launch

[kinyo]

i agree about higher fuel consumption with D engaged while the brakes are applied ... it is an additional 0.5 li/hr on my car as it needs more power for the additional load

but ...

with D engaged, brakes applied and car not moving, why do you guys say it tends to wear out brakes?

if the car is stationary, there is no rubbing friction between pads and rotor, no heat generated ... how do the brakes wear out in this condition?

[Automahn]

+1 here. even though the stops are quite low like let's say, 30 seconds, it is still moving, so the load is on the transmission as well as on the brakes.

it is better if even in short stops, that you put it in neutral. you save gas, you save your brakes, you save your transmission. and besides, i think modern AT assemblies are very durable to do that.all it takes is one click of your hand.

You save on your stop light bulbs as well.;)

[rion]

there is no rubbing friction between pads and rotor, no heat generated ... how do the brakes wear out in this condition?

like mentioned, just by a bit...

comparing our own A/T and M/T ride, mas malakas ang brakes consumption ng aming A/T.

in my case, it's faster to pickup speed on standing start traffic light to use N then flooring at D. than staying on brakes then flooring to D. because somehow when you put from N to D, you get a kicky start-up feeling. though I hear about brake torque but I have no idea what it means...

[niky]

Why will putting it in "N" starve it or destroy it? The internal oil pump is continuously active as long as the engine is on. Whether or not there's any load on the torque converter, the internal fans are still spinning, so it's still being lubricated continuously.

Putting it into neutral then into drive at idle does not damage anything, as the clutches are stopping a light disc spinning at merely 800 rpm.

There is much more stress and heat on the whole torque converter assembly when accelerating before the converter locks-up (at somewhere between 2000-3500 rpm, depending on the car) than there is in shifting to Neutral at the stoplight.

You can feel this on some high-powered engines... the stress on torque converters during pre-lock-up acceleration is really high, and you can feel the heat coming off the transmission housing by your leg. That's why most stock converters are built to lock-up at low rpms, to minimize the amount of time during which the two ends are spinning at different speeds.

When you put it in "D" at the lights, you connect one end of torque converter to the drivetrain. So one end is spinning at 800-900 rpms, the other is locked to your drivetrain, which is locked in place by your brakes. This generates load, which uses up fuel... and it also generates heat. Tons of heat if you're sitting at a light for more than half-a-minute.

This heat leads to the premature breakdown of your transmission fluid, which will harm your torque converter, which will lead to an awful overhaul bill in the future.

And an awful amount of burned brake pads in the short-term, too.

So... if the manufacturers want to limit the time that the torque converter spends unlocked and under load... shouldn't you, too? ;)

[rion]

I don't think it will starve atf if you put more on N. measuring atf level while engine running on D, N or P have the same reading unlike not turning engine on.

I think putting it to D won't make much difference for non-efi a/t's. since it doesn't have computer or sensors to detect it is running low on power that tells it to feed more fuel to compensate the felt load.

but putting D worn out engine support by a bit, brake pads by a bit.

and I would like a faux sunroof for my car.

[chr1smj_15]

never leave on "D" mode for a long period of time for safety reason

[corbon44]

errr...just to add to the options - does anyone shoft to "park" (P) while in traffic and the engine is running? what happens here and what implications does this have to the drivetrain?

[ooba99]

I think a non-moving a/t vehicle on D with brakes applied on consumes more fuel because there is stress on the engine. This may be negligle though. It had been my habit to place the transmission on N whenever I am in a full stop and anticipate to be so for at least 30 seconds, like in a stop light or in a traffic jam.

[pup2]

errr...just to add to the options - does anyone shoft to "park" (P) while in traffic and the engine is running? what happens here and what implications does this have to the drivetrain?

Dude, pag nabangga ka kahit mahina lang, bye bye tranny/drivetrain. Please read earlier posts.

[suysuy]

what i do talaga is if nakita ko sa malayo na red na, i shift to N agad. hanggang sa maka abot sa dulo. saves fuel. then if stop na talaga, N talaga ako nyan.

common sense lang, Pag D ka na strestress ang engine kasi naka engage tapos naka brake kapa. its my habit na naka N parati pag stop. pag uphill, ibang usapan na yan, leave it to D or if mag N ka make sure naka brake ka rin. and if mag start na mag move, shift it to D first before releasing the brakes