Dsg shifting in/out of neutral?

Does shifting in and out of neutral to coast at idle cause any excess wear on the transmission? I noticed without shifting to neutral, the car downshifts during a coast to stop, keeping the rpm higher. In testing this, I did see improved mpg, but prefer not to damage something.

Reading about hypermiling, I read about "pluse and glide" on non hybrid cars. Does anyone have experience with this in a newer passant tedious? It seems like the starter and trans, would get allot of extra wear and tear?

Having read all of the mileage threads, I'm a bit confused on the optimal speed and rpm for the maximum mpg on a level highway? I have read that @ 1800 rpm or 65 mph is optimal; I also read that just after the automatic shift to 6th gear, maintaining the lowest possible rpm is the best mileage. Does anyone have experience with this?

Thanks for input

The WHOLE time your foot is completely off the accelerator, and the RPMs are even a slight bit above idle speed, the injectors are injecting ZERO fuel. If you coast in neutral, the injectors are injecting fuel to maintain idle speed. So coasting in neutral wastes fuel.

Since wind resistance is proportional to the square of your speed, the lowest possible speed in the highest gear is absolute maximum fuel economy.

You should be in manual mode, 6th gear, and just above the RPM where engine lugs. That would probably be 40 MPH, but that would be impractical for highway travel, so for that 55 MPH would be ideal, except you'd irritate others on the road in 70 MPH zones!

The DSG is very expensive to replace. Let the computer do the downshifting, and don't move to neutral. Your MPG gain going to neutral would be negligible. In fact, I wonder if you are gaining any MPG, as when you're coasting, regardless of what the tach shows, fuel flow is cut off. In neutral, fuel is still flowing to maintain idle.
As for cruise MPG, I'm going to guess your optimal cruise speed, in 6th, is probably around 40-45 mph. Not very practical on the open highway, though...

Thanks. I'm certainly no expert, but regarding the fuel cut off while coasting? I have a long steep 1mile hill I go downhill on, if I break the crest at 35 mpg, 6th gear and coast in gear, the car downshifts raising rpm to 5th, 4th . If I shift into neutral at the crest, and coast, the gravity roll increases speed to 60mph or higher. So if I understand correctly, the downshift/rpm increase is mechanical driven, not by fuel burn? Maybe a safety thing.
On the level terrain the downshifting also occurs while coasting in "d". I was thinking a neutral coast to the red light was more fuel efficient than auto downshifting, where I need to throttle up just to get there?

If you're coasting, regardless of RPM, there is no fuel flowing.

The manual states never to coast in neutral because "the transmission will not be lubricated and will be damaged".

Coasting in neutral is also very dangerous since you longer have power going to your wheels. Excessive braking also causes overheating, degrades braking performance and could lead to brake failure.

I love the way the DSG behaves like a manual when slowing or going down hills. I often use my tiptronic (paddle shifters) in some situations to down-shift sooner while slowing, and/or going down hills.

tdiatlast said:

Your MPG gain going to neutral would be negligible.

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Incorrect! It would be a loss.

The DSG is a little aggressive on downshifting when the brake lights are lit regardless of amount of brake pedal applied... when I want to coast I just use manual mode and select a gear to keep the RPM just above idle so the injectors remain off

jrm said:

when I want to coast I just use manual mode and select a gear to keep the RPM just above idle so the injectors remain off

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Actually, all you need to do is select manual mode, for slower than normal downshifting. You don't need to tap the shifter at all; it automatically still downshifts, just at much lower RPMs.

I wouldn't chance Neutral coasting with the DSG. In regards to your optimal MPH for MPH, I have found the slower the better. I have a manual transmission and 55 MPH returns killer MPG. Anything faster and the MPG goes down. I'm not sure that the DSG will hold 6th at 55 MPH, but I assume that it would on flat ground at least.

psd1 said:

I'm not sure that the DSG will hold 6th at 55 MPH, but I assume that it would on flat ground at least.

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It will, if you go to MANUAL mode!!!

it does hold quite well, takes quite a bit of throttle to get the DSG to downshift at 50-60mph, I find it lugging at 1,300RPM often

jrm said:

it does hold quite well, takes quite a bit of throttle to get the DSG to downshift at 50-60mph, I find it lugging at 1,300RPM often

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There is hope for man after all!

Never, ever shift an auto into neutral just to try to gain MPG. You're trading transmission wear for what's probably a negative impact on your gas usage, because of what people have already pointed out (neutral = fuel flowing, in gear and not accelerating = fuel is cut off). If you want to maintain speed while going downhill, shift over to manual mode on the DSG and upshift to higher gears to lessen the engine braking.


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Canuck64 said:

The manual states never to coast in neutral because "the transmission will not be lubricated and will be damaged"...

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Yes thats true but the only place I have found it in the manual was in the context of the engine not running. But I still wouldn't do it regardless.

Justinw303 said:

Never, ever shift an auto into neutral just to try to gain MPG. You're trading transmission wear for what's probably a negative impact on your gas usage...
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The wear would only occur if the engine weren't running. And thats because the trans oil pump is driven by the engine. As long as the engine is running and the pump is functioning, the trans is receiving lubrication. Even so I would never advocate shifting into neutral while in motion except for an emergency situation. The practice otherwise is...well...just plain silly.

thanks for all the great input; i had a chance to test some of the advice that was offered.
i drove 75 miles, first 3 miles and last 5 miles in stop and go city, 67 miles on highway. I left the car in gear(no neutral coasting) and speed ranged from 50mph up hill to 60 downhill. the trip avg said 54mph. temp was 17 f. the cpu milage said 50.7 mpg. i was duly impressed.