Vacuum gauge instead of Scangauge?

[Rick Rae]

Originally Posted by brucepick

...I think it would be difficult or impossible to show that you can coast in gear as well as you can coast in neutral.

You could safely drop the "difficult or" in a vehicle without fuel cutoff (as mine appears to be).

...let's not fool ourselves into thinking it's going to get you as far on the same fuel compared with coasting in neutral.

If someone suggested that, I missed it. I certainly don't think that's the case. You guys with stick shifts have it all over us automatics in that regard (as well as others).

Originally Posted by viper75

Maybe I misunderstand what you are saying here but I can't see how this approach could be as good as coasting in neutral (at least for FE, safety is another question).

You didn't misunderstand, you merely overlooked.

FE-wise, I absolutely agree that coasting in gear can't match NICE-ON coasting... which in turn pales in comparison to EOC. The bit you might have overlooked is this:

Originally Posted by me

I wouldn't even bother with that, but A) I've yet to see evidence that my car does fuel cutoff, and B) throwing my automatic in and out of neutral at highway speeds makes me uneasy (when I think about it ).

I can't safely EOC with my automatic. I've watched my transmission temperature climb unnervingly high during NICE-ON experiments, I sometimes think I hear disturbing sounds bouncing off of reflective surfaces when I drop it back in "D," and I don't have a definitive answer to whether NICE-ON coasting is safe for my vehicle. And my engine doesn't appear to cut fuel during in-gear idle coasts, so I can't trade off zero fuel use against engine braking.

That leaves trying to feather the accelerator into the "Goldilocks region" as one other option to explore, which is all I'm doing: exploring. I'm not offering it as a recommended or even useful technique at this point; I'm too new to all of this... crawl before you walk, and all that. I just gave it as another example of where you'd have to weigh this against that to determine which approach was better for a given situation (vehicle, driver, traffic, etc.) Apologies if I muddied the waters by mentioning it at that point.

Originally Posted by viper75

I think what you are describing is giving the engine just enough gas to overcome the effect of engine braking so that your speed at any point on the hill will be equivalent to what it would be if you were coasting in neutral.

Correct.

...you would burn the same amount of gas by this approach as coasting down the hill in neutral with the engine revved to the higher rpm...

Seems about right. The other effects are that A) you'll glide farther than you would if you took your foot off the gas and subjected yourself to engine breaking, and B) you'll use less gas than if you keep the throttle locked. Where's the sweet spot? Dunno, but playing around with it is one way to find out.

I would actually like to be wrong about this because I would rather coast in gear then in neutral if the FE is the same.

I don't think you're wrong. No way would you come up with the same numbers. I doubt you could even get close and that's assuming perfect control of the gas, which brucepick and I both implied would be nigh onto impossible.

If I can get half the efficiency of a NICE-ON glide I'll be pleasantly surprised. As you both said, I'm giving the engine fuel to keep it at speed the whole time, after all (even if it is unloaded, assuming a perfect rev match).

Originally Posted by brucepick

If a driver just doesn't find sufficient control with the engine in neutral I won't disagree with their own perception... If spinning the engine is of value to the driver then OK.

For the record, I don't have that perception, and the value to this driver is not destroying either of my transmission or my nerves.

Honestly, I want to NICE-ON coast (heck, I want to EOC glide!). I've been playing with it; I love the velvety feel, I love the MPG numbers. But until I feel confident it doesn't put excessive stress on my transmission or TC, I'm not going to push it. In the meantime, I'm playing with whatever other techniques I can think of to see how close I can get to the same fuel efficiency. Maybe I'll settle on coasting in neutral at low speeds and something else on the highway; who knows at this point. Like I said, I'm new.

I hope that clarifies things a bit?

Rick