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I saw a guy on youtube doing this, and have given it a shot a few times. It does seem to help the FE, but I'm worried about messing up the transmission.

The times I tried it were generally when I saw a red light up ahead, but it's far enough away that it will probably change by the time I get there. I shift to neutral and coast until the light goes green, and then shift back to drive. When I shift to drive, I may be going 30-40mph.. would that hurt anything?

Then there were other people who were shutting off the engine entirely, then turning it back on when they needed to accelerate some more. I doubt I'm ever going to get *that* serious about hypermiling, but I'm curious how many more miles you can squeeze out of a gallon doing that.

I'm still training my foot.. and I do have those glorious moments where I can coax 100+mpg for mile or more stretches at 37mph, but then I ruin it with poor acceleration control at the next light. I'll get there, but for now I'm trying just about every trick I read about to see what will work best for me.

Front tires are at 42psi and back tires at 40psi. I got a digital tire pressure gauge and found that when I thought they were already at 40, they were actually 38. Stupid gas station analog pressure guage lied to me. :(

I got my ICE firmware upgraded today at the dealership, and I'm still getting plenty of assist, and was at auto-stop at a light for over 60 seconds, so the things I was worried about getting ruined seem to be ok. I also stayed at like 5 bars of charge for the 10 mile drive home instead of dropping out like I had the past 3 days.

I'm obsessed with car.. :P

Do I shift into neutral and coast?
No. Doing that lets the ICE idle away while coasting and that is not desirable.

Do I shift into neutral with the engine off while coasting?
No. That is, not unless I have members of the press in the car while demonstrating 90+ MPG driving in the HCH-II. ;)

It's not that it damages the transmission especially if you take the time to do it right. The problem for me is that is helps deplete the SoC faster and it resets your operational stages thus cancelling all specific hybrid features for a 10-15 seconds gap and that to me is not a desirable thing to do on a regular basis.

My strategy has been and will continue to be focused on leveraging the features the engineers designed into the car which when paired with good maintenance of the vehicle will be the only guarantee of a long, dependable and trouble free operation of the HCH-II.

So as far as coasting goes, my primary means of coasting consists of inducing a soft-glide (done with the accelerator pedal only). Its simple and it works quite well and while not as good as coasting in neutral with engine off it works OK without the ill effects I aim to avoid.

Cheers;

MSantos

So as far as coasting goes, my primary means of coasting consists of inducing a soft-glide (done with the accelerator pedal only). Its simple and it works quite well and while not as good as coasting in neutral with engine off it works OK without the ill effects I aim to avoid.


With the extra special bonus that it does not constitute unsafe driving worthy of a ticket, which is the prize one should expect to receive from coasting with the motor off should a member of the highway patrol observe it.

With the extra special bonus that it does not constitute unsafe driving worthy of a ticket, which is the prize one should expect to receive from coasting with the motor off should a member of the highway patrol observe it.

Probably technically true but highly unlikely, they have so many other things that they're busy not ticketing for and would be pretty difficult to notice and harder to prove.

With the extra special bonus that it does not constitute unsafe driving worthy of a ticket, which is the prize one should expect to receive from coasting with the motor off should a member of the highway patrol observe it.

The technique of gliding with the engine off is certainly not for everyone and every circumstance as such, we often refer to it as an advanced technique!!!

And like all powerful/advanced techniques, it is to be used only by folks who mastered the hypermiling basics first and only then, where permitted and safely applicable.

Cheers;


MSantos

What would be ya'lls answer if the car/truck inquestion was a non-hybrid vehicle? Would shifting the trans into neutral be bad?

What would be ya'lls answer if the car/truck inquestion was a non-hybrid vehicle? Would shifting the trans into neutral be bad?

As long as the engine is running, there's no harm done. There have been a few examples of automatic transmissions where the owners manual has stated that coasting in neutral is not recommended, so it's always a good idea to check the owners manual. All GM transmissions built in the last 45 years can coast in N with no problems, and can also return smoothly to D at any speed without rev matching - just move the lever to D and accelerate after a second or two.

There are some automatics that are also flat towable, which means they can tolerate coasting with the engine off, and therefore no oil pressure within the transmission. There are speed and distance limits assigned to this capability, and it is listed in the owners manual in the "towing" section. This capability refers only to coasting with the engine off, and not with the engine running, as noted in the original post.

Your Silverado can handle coasting in N without a problem, as long as the engine is running. I don't believe it is flat towable (it is a computerized version of the old TH700R4), but for your purposes - coasting with the engine running - that is not a critical attribute.

What would be ya'lls answer if the car/truck inquestion was a non-hybrid vehicle? Would shifting the trans into neutral be bad?

Depends.

If it's a 1960 manual (no locking steering wheel and no power anything) you can put it in neutral and turn off the motor and it will brake, steer, and handle as well as before. Well, it won't quite brake as well because there is no engine braking, and that would make a difference when descending a grade.

On a typical 2010 car putting it in neutral and turning the key to off may cause the steering wheel to lock and will eliminate the steering assist and cause the brake assist to fade out after a a pump or two. A 2010 manual transmission won't be damaged by gliding in neutral (with the motor still running, so you don't lock the steering and crash), but don't do it by gliding with the clutch in. For an automatic I wouldn't do it. Especially if the manual says not to tow it with the drive wheels on the ground. That pretty much tells you that that is one of those automatics which is only cooled properly when the motor is running (motor turns transmission which circulates fluid to cool). Tow it or coast it for very long and it will overheat the transmission, which will cost a heck of a lot more to fix than whatever you might have saved in gas.

Depends.

If it's a 1960 manual (no locking steering wheel and no power anything) you can put it in neutral and turn off the motor and it will brake, steer, and handle as well as before. Well, it won't quite brake as well because there is no engine braking, and that would make a difference when descending a grade.

On a typical 2010 car putting it in neutral and turning the key to off may cause the steering wheel to lock and will eliminate the steering assist and cause the brake assist to fade out after a a pump or two. A 2010 manual transmission won't be damaged by gliding in neutral (with the motor still running, so you don't lock the steering and crash), but don't do it by gliding with the clutch in. For an automatic I wouldn't do it. Especially if the manual says not to tow it with the drive wheels on the ground. That pretty much tells you that that is one of those automatics which is only cooled properly when the motor is running (motor turns transmission which circulates fluid to cool). Tow it or coast it for very long and it will overheat the transmission, which will cost a heck of a lot more to fix than whatever you might have saved in gas.

The steering wheel does not lock unless you turn the key past ACC to the OFF position. On modern AT vehicles, there is an interlock that prevents you from turning the key to the off position unless the shifter is in Park. And you can't remove the key until the switch is in the off position.

When the engine is off, you lose power steering assist if it is a hydraulic power setup. On my EPS car, you do get some steering assist, but not much - probably because the current draw is too high for the battery alone to provide. Without any power assist at all, I can steer my nose-heavy 3500 pound FWD car without much effort until speeds drop below 10-15mph (depending on road surface). Effort increases dramatically as you steer further away from straight ahead (due to caster angle), but I don't know anyone who cuts the engine at any point before a low speed sharp 90 degree turn.

As you noted, you keep the power brake assist for 2-5 presses of the pedal if it's a vacuum assist setup (hydroboost brakes lose power assist).

The issue with automatics coasting without the engine running is not one of heat, but rather the lack of fluid circulating to lubricate the rotating internal parts. When the internal bushings run dry, they wear at a rapid rate. As long as the engine is idling (as in NICE-on coasting as opposed to NICE-off), this is not an issue on any automatic. Even idling, there is enough fluid volume and pressure to keep everything properly lubricated.

That being said, I remember one member here with a Mazda-sourced automatic who wrote that their owners manual stated that coasting in neutral is not recommended and can damage the transaxle. But there is no way of knowing if the disclaimer is there to avoid damage by people overshooting N and getting to R or P, or if the electronic controller would actually have a brain-fart by trying to apply first gear when shifted to D instead of reading the VSS and choosing the correct ratio. Some older Ford transmissions have also been observed having a computer-convulsion when returning to D, but those units are no longer in production.

For any MT vehicle, shifting to neutral is harmless. You're actually doing it briefly as you shift gears. Doesn't matter whether the engine is on or off.

For automatics, shifting to neutral is fine while the engine is running, as long as you check the owners manual for any lawyeresque messages, preceded by a triangle with exclamation point, stating you must never (or should never) shift to N while the car is moving.

Engine off coasting in an automatic requires that you confirm that the car is flat towable, as outlined in the owners manual, and that you observe the speed and distance limitations.

What would be ya'lls answer if the car/truck inquestion was a non-hybrid vehicle? Would shifting the trans into neutral be bad?

I did this on my previous vehicle to the HCH-II, a 1989 Toyota Corolla with 5-speed manual. I always pushed in the clutch when coasting, and started hypermiling it the last year I drove it. I descended some long hills with the engine stopped, and coasted up to all lights with engine off. Steering got stiffer, and you had to be ready to REALLY lean on the brakes if the vacuum booster got drained. It changed city mileage from 30 to 35 MPG with those tricks.

(Just an aside - a friend of mine, many years ago, had the habit of coasting into parking lots with the engine off. One time, he forgot to push down the clutch, and it sounded like we ran over a land mine! He blew the muffler up but good! Won't happen on today's fuel-injected cars, of course.)

Jon

The steering wheel does not lock unless you turn the key past ACC to the OFF position. On modern AT vehicles, there is an interlock that prevents you from turning the key to the off position unless the shifter is in Park. And you can't remove the key until the switch is in the off position.

In my car, a '96 Accord, not only do I have to put the car in park to turn it to the OFF position, but I have to push the key in as I turn it to OFF, and the steering wheel won't lock until I take the key out of the ignition.

An easy test to see when your steering wheel will lock is to do it when stopped. Turn the key to ACC and see if you can still turn the wheel, then OFF, then key removed. It may take half a turn of the wheel to get it to lock, but you will hear the click as the wheel locks. At least that's been the case in every car I have owned.