So Close!!!!

[Altitude]

Originally Posted by auxmike

Also, isn't it REAL bad to throw an auto into neutral while rolling?

That's one of those things I've always heard too, but never heard the why of it. Anyone here know?

[auxmike]

Even the owners book tells you to raise the front wheels when pulling an auto behind a motorhome.

[twowheels]

Originally Posted by Altitude

That's one of those things I've always heard too, but never heard the why of it. Anyone here know?

My understanding is that the transmission fluid pump is driving by the input shaft from the torque converter. If the engine isn't turning the torque converter then the pump isn't moving fluid around the transmission, but everything's still spinning at high speed. This may not be true of the Yaris as it doesn't DFCO, but I really don't know.

Manuals, on the other hand, work as an oil bath IIRC... the bottom of the spinning gears are always in the gear oil picking some up and moving it around the transmission.

[Yaris Hilton]

Originally Posted by twowheels

This may not be true of the Yaris as it doesn't DFCO, but I really don't know.

Yaris automatics from something like January 2007 build dates (I think) do have DFCO in Drive. Earlier ones did only in lower gears; why they set them up that way I can't imagine. I don't do neutral coasting, but if the engine's still running it can't hurt anything.

[aclark246]

Believe me, I NEVER thought I would do neutral coasting. It was always one of those techniques I had reserved for manual transmissions. I just did a heck of a lot of research before I tried it for the first time. (There was no way I was going to jeopardize my car or transmission for a few extra dollars at the pump, and definitely not my safety.) The safety issue for me was easy: if manuals can pull it off with out endangering the driver, so can automatics. Just like any other technique, it has to work with your commute and with the particular driving/traffic conditions. For instance, in heavy traffic where it would not be safe (too fast,) I DO NOT neutral coast. In that aspect it is just like being a responsible driver, knowing your car and the road conditions. You have to be responsible, observant, and respectful.

The safety/longevity of my transmission and other car parts on the other hand was hard to get over. From what I have read and discovered, (mostly online at gassavers.org and cleanmpg.com,) MOST automatic transmissions can neutral coast safely, including ours. (One exception I found was, and I think Bailout actually discovered it, Chevy Aveo's cannot neutral coast with the engine on.) Yes, our cars cannot be dingy towed, meaning we CANNOT neutral coast with the engine OFF. From what I understand, being in neutral with the engine ON is still perfectly fine, and there is minimal wear on the transmission when shifting back and forth. (I personally don't shift unless it will be at least a 0.5 mile coast.)



My word is nowhere near fact! Neither are the words of the folks on gassavers or cleanmpg! I just did as much research as a could, (member Voodoo22 was a big help,) and made my best judgement. It is the same as any technique, it has to be right for you and you have to be ok with it. But, from what I have as experiential evidence, (unfortunately not enough scientific evidence, which is why I'm not going to tell anyone to do it on my word alone,) neutral coasting with the engine on at speeds under 60 mph is not only safe, but it is a good alternative to DFCO on those occasions where DFCO would slow you down too much.

I still use DFCO because nothing beats FREE miles, but at segments of my commute I can get 1-2 miles in neutral for the price of idling the engine where DFCO would have given me maybe 0.5 miles and the rest using gas in Drive. I estimate, I added at least 15 miles on to my tank of gas by neutral coasting. And I think I can add more next time!

I understand many of your reservations to the technique, and I don't want to push you to do any of it. (I have taken the responsibility of my own car and transmission, and if what I do messes it up I am the only one to blame. I don't plan on it, but I am taking the responsibility for it. I don't want to be responsible for anyone else's cars though, ha ha.) So yeah, as a disclaimer, don't do anything just because you see it on a forum, but from what I discovered, (and it is adequate enough for ME,) neutral coasting with the engine on in an automatic yaris sedan is great.


EDIT: On a side note, I DO have a very basic and sort of controlled ongoing experiment. My girlfriend has a 2007 yaris as well, manufactured two months before mine with the same packages and same transmission. We do all of our maintenance around the same time, (although she has about 10k more miles than I do.) Essentially, my car is the hypermiling as a sport car, and hers is the just drive responsibly car. She got about 40 mpg on her last tank, (also a lot of highway,) but gets between 32-42 the rest of the year which we can't complain about. I do not neutral coast, and neither does she in her car. The only things she does is stay below 65 as much as possible and accelerate smoothly, (driving responsibly.) We do use A/C in her car freely however since it isn't as much of a sport to her as it is to me. So seeing as we both plan on keeping the cars for as long as possible, I will be able to provide experiential updates if I need any special services before she does, or vice versa. We can then see if they connect to driving habits or conditions, or if they are unrelated to hypermiling. So in 10 years I'll be sure to post my results if I kill my transmission significantly sooner than she does, or if anything else goes wrong out of the expected realm.