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Old 5th December 2010, 19:21   #1
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Default Automatics : P or N at signals / traffic lights?

In an AT vehicle, what is the best way to idle at a traffic signal? Shift into Parking, or get into Neutral and pull the hand brake, or simple stay in Drive with the foot on the brake? A prospective Endeavour owner asked me this question, and suddenly I wasn't too sure of what the right answer should be. Any thoughts, guys? What would be the best option in terms of maintenance and longevity of the clutch/transmission assembly?
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Old 5th December 2010, 19:55   #2
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>>>

For stoppages of about upto a minute or so, as is so often the case in city driving in India, I put it in N and keep my foot on the brake. If it is more, it is P for me. Keeping your foot on the brake and on D while you have stopped, for durations of around a minute will wear your brake pads.

Also, consult the manual of the vehicle in question; more often than not the manual is the best reference and guide, rather than hearsay.

Regards, drive safe
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Old 5th December 2010, 20:08   #3
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+1 to issigonis.

Also while in the US its ok to keep the car in D and foot on brake as you can stay a good 10 feet behind the car in front. No one is going to cut into that space. In India when you need to stop less than 10 inches behind a car, a slight shift of the foot will result in a fender bender.
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Old 5th December 2010, 20:32   #4
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Quote:
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>>>

For stoppages of about upto a minute or so, as is so often the case in city driving in India, I put it in N and keep my foot on the brake. If it is more, it is P for me. Keeping your foot on the brake and on D while you have stopped, for durations of around a minute will wear your brake pads.
In my 3 years of driving an automatic in the US, I used to always keep the car in D and use just the brake pedal when stopping at signals. Not sure if that was the right thing or not, but it certainly was the easiest thing to do.

Also are you sure the brake pads would take a hit if you do this ? The car isn't in motion, so why should the brake pad wear out ? (Yes the transmission would be slipping, but in an AT system, it is designed to allow that slippage - right ?)
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Old 5th December 2010, 20:47   #5
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Having driven automatic cars in India, what I usually do is put the car in N, pull the hand brake and sit tight till the light goes green. (If the signal is a long one)

If its a really short signal, its better to just put the car in N and keep your foot on the brake.

Putting the car on D at signals only keeps the car in gear and will wear your brake pads faster.
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Old 5th December 2010, 20:50   #6
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I drive the Corolla AT. I keep it most of the time in D with my foot on the brake pedal. Unless I know for sure that I will not move for more than a minute, I continue to be in D. If I know that I'm going to be stationary then I gently nudge the gear level to N. P is only for parking the car and when I'm going to get out of the car. In a Corolla, the ignition key cannot be removed unless it is in P.

In India, while standing in a signal, most of the time, there will be a slight forward movement in the traffic even with the red light. It is advisable to keep it in D with foot on the brake.

Last edited by MAS : 5th December 2010 at 20:54.
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Old 5th December 2010, 21:07   #7
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P would be quicker and better
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Old 5th December 2010, 21:32   #8
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+1 to funkydevil - that's spot on.

I don't recommend keeping in D and foot on brake either if you're stopping more than 5 - 10 seconds.

Ideally just put it in N and either pull the handbrake or step on the reg brakes if required. Putting in P is really unnecessary for temporary stops while driving - you're unnecessarily traveling across the gear range through R.
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Old 5th December 2010, 21:46   #9
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Quote:
Originally Posted by kala View Post
In my 3 years of driving an automatic in the US, I used to always keep the car in D and use just the brake pedal when stopping at signals. Not sure if that was the right thing or not, but it certainly was the easiest thing to do.

Also are you sure the brake pads would take a hit if you do this ? The car isn't in motion, so why should the brake pad wear out ? (Yes the transmission would be slipping, but in an AT system, it is designed to allow that slippage - right ?)
thats correct, brake pads won't wear out if you are completely stopped. Also, it will be quicker to keep it in 'D' unless you have very long signal with a timer.
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Old 5th December 2010, 22:42   #10
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There was a discussion on the same topic in Automatic Transmission v/s Manual thread.
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Old 6th December 2010, 15:57   #11
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Here's a great thread for tips on driving Automatic Cars : Linky
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Old 6th December 2010, 22:21   #12
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Abes/GTO - thank you so much for the pointers. Have shifted to D + brakes for mini stops (gotta be careful you don't let the vehicle slip slowly forward), and N + hand brake for slightly longer signals. P only when parking
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Old 21st August 2012, 18:53   #13
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Default Automatics - selector position at stop lights

I was wondering - does an automatic burn more fuel when idling on D vs. idling on N? It seems to me that because the transmission and drivetrain are engaged on D (and hence the creep) it should be burning more fuel on D. And I'm using the brake to keep it stationary. If that's the case, shouldn't I switch to N or P at red lights?

Any insight appreciated!
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Old 22nd August 2012, 10:04   #14
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Default Re: Automatics - selector position at stop lights

Quote:
Originally Posted by VANdaMAN View Post
I was wondering - does an automatic burn more fuel when idling on D vs. idling on N? It seems to me that because the transmission and drivetrain are engaged on D (and hence the creep) it should be burning more fuel on D. And I'm using the brake to keep it stationary. If that's the case, shouldn't I switch to N or P at red lights?
Yes, an At does burn a little more fuel at stop lights. It is the torque converter which is guilty. My own procedure is to shift to N if the stop is likely to be long, else stay in D.
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Old 22nd February 2013, 10:15   #15
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Default Re: Automatics : P or N at signals / traffic lights?

N mode + Parking/hand brake is the best combination (no wear on transmission and life of brake lights is not shortened)

N mode + foot brake (shortens the life of brake lights)

D mode + foot brake (transmission wear and shortens the life of brake lights)

P mode is same as N mode with transmission locked with a mechanical 'pin'. Should not be used without locking the wheels with brake because this 'pin' can wear and break. Trying to hold the car at stop with P mode is equivalent to stopping the car with a 'pin' that locks the transmission shaft. Can put a lot of stress on this pin if the car is on incline ,etc. so P mode should always used with brakes just like N mode. I would like to think that P mode doesn't exist for the driver and it is just meant for the car's computer to use P when you switch off, AT breakdown, etc.

I always try to use N + Hand brake because in the past I changed brake lights prematurely and they are not cheap. Fuel consumption difference is negligible compared to mechanical wear among the above options.

Realistically, transmission wear is not so bad that you would incur expenses due to stopping in D mode. I would be more concerned about brake lights and brake pads which have much shorter life if care is not taken. That is why I prefer hand-brake to foot-brake at signals. You also don't blind the poor soul waiting behind you.

Of course, manufacturers are constantly making the transmissions smarter.

For instance in 7sp AT in BMW - D + Brakes is same as N + Brakes because the AT is intelligent enough to shift to N during D + Brakes. When I release the brake, I actually can sense the N to 1st Gear change happening. It doesn't shift to N if in sports mode btw. So if you are in BMW 7sp AT car, you can always do D + Brake instead of N + Brake.

Another development is Auto-hold. Auto-hold is a smart foot-brake. Your brake lights are ON when brakes are applied by auto-hold. You can drive off without releasing auto-hold ("auto" see!). With this feature ON, you just have to come to a stand still and relax - BMW 7sp will shift to N, and apply foot-brake for you.

One more related feature is electronic parking-brake. Your brake lights are OFF while Parking-brake is applied. If you forget to release electronic parking brake and drive off, the parking brake is automatically released after few meters. So saves you those "ooops" moments when you forget to release hand-brake lever :-)

Last edited by androdev : 22nd February 2013 at 10:17.
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