We have a 2005 Saturn Ion with an automatic transmission. My husband always shifts it into neutral when he approaches a stop light, stop sign, or if traffic slows down and then he shifts it back into drive when traffic starts to move. He also shifts it into neutral when he goes down a hill. I wonder if this is a good idea as far as safety is concerned as well as if it’s good for the car.
Respectfully . . . your husband is wrong
Just keep the car in drive, and apply the brakes, as needed
Your husband is complicating things that should be simple
That’s unsafe, in my opinion
If he wants to shift to a lower gear ratio going down a long and steep hill, that’s one thing. But shifting into neutral is not what I’d recommend
Where’d your husband pick up those habits . . . ?!
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You asked where he learned these habits. I don’t know, but I think he’s saving gas.
You cannot do a kindness too soon, for you will never know how soon it will be too late.
Ralph Waldo Emerson
[quote=“Nelly28, post:3, topic:123770”]
You asked where he learned
Not in my opinion
I really have no idea why you brought Ralph Waldo Emerson into this . . . ?! 
Since he’s shifting in situations when he wouldn’t be accelerating anyway, I do not see that there’s any gas mileage improvements. It doesn’t help in braking any further so it’s not a helping the brakes last any longer. Disengaging the transmission takes control away from the driver. It increases the chance (albeit a small chance) of shifting into the wrong gear (like into reverse when going forward). And it’s teaching this practice to the children if you have any (can you imagine a 17-year-old doing this flawlessly?).
I just don’t see benefits and I do see a couple big negatives.
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ah, he sees the rpm at 1300 rpm while he goes down the hill and computes that if he is in neutral the motor will idle down to 800rpm so for the those 14 sec he will have better mileage. only reason i can see. sounds like a hyper miler trick too me. next he will shut off motor at stoplights.
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Even if hubby did save a miniscule amount of gas, the fact is that he is using his brakes more than he would if he simply left the transmission in gear. He is placing more wear and tear on his brakes, and ultimately this will cost far more than the few pennies that he might–in theory–be saving by shifting to neutral.
And, this practice is NOT safe.
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Automatic transmission have what’s called an over-running clutch inside the transmission to do exactly this. Tell him to stop this.
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You’ve gotten lots of good correct answers so far. I’ll also point out that this is illegal in at least some jurisdictions because it’s less safe. He should stop doing this.
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He’s using more gas (by a tiny amount) I bet. The fuel injection can shut off on deceleration, but not on idle.
And it’s unsafe to be in neutral going down a hill. It puts a greater load on the brakes.
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Probably an automatic signature attached to email, OP responded to you via email
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People who reply by their email some have tag lines that are on all of their emails. Why I don’t know .
Did hubby learn to drive on a manual transmission? If so, he may have brought forward a habit appropriate to manuals to automatics, where it isn’t.
It is illegal in Oregon for at least 52 years (when I studied for my learner permit). Possibly due to all the mountain ranges we have.
Similarly, I don’t have a current NJ DMV manual, but I do know that coasting in neutral was prohibited when I studied for my DL, about 53 years ago. I would be very surprised if it was legal today.
Shifting into Neutral to slow to a stop or go down a hill is silly. I can’t say much about the danger, as overheating brakes on most modern cars is no mean feat, but as for the gas mileage, it is counter productive. Modern engines have an “over run” mode. If you leave it in Drive going downhill, it will either drop the engine to an RPM slightly above idle, or if the hill is a bit steeper, it will drop to a lower gear to pull the RPM up a bit. In either case, the fuel system will usually shut the fuel off completely, as it is not needed. If he puts it in Neutral, the engine needs fuel to idle.
The way engine computers work these days, completely turning off the injectors when they aren’t needed, shifting into neutral probably doesn’t save any gas. But whether it does or not, the difference in gasoline usage would be pretty small. The most important safety issue imo is that when coasting in neutral, it takes extra time to engage the transmission and speed up should that be necessary to avoid an upcoming traffic problem. However, there’s a safety upside to counter that, when stopped at the traffic light it is less likely he’ll accidentally move forward and run into the back of the car in front, or run into a pedestrian crossing in the crosswalk. So in normal urban and suburban traffic situations, I’d guess it is a wash safety-wise. On long, steep down-hills it could be unsafe if he has to apply the brakes more, as the brakes could overheat.