The Proper Way To Coast

[LarryKingsShoes]

Greetings!I spent part of the day reading about hypermiling tips in an effort to get the most out of each gallon of gas that I consume. One of the seemingly best methods of boosting fuel economy was to coast whenever safe and practical to do so.In a 2003 Vibe GT (6 speed manual), what is the best way to coast? I've read about a couple of different techniques but wasn't sure which was the best way for this car.The method that seems like it'd be the most efficient would be to shut the engine off and then pop the clutch into gear once necessary. My concern with this is that it isn't quite as safe as the others. Between the loss of power steering (which doesn't really bother me as much) and the potential issue of braking, there are some consequences to this approach that make it less than practical. I feel comfortable with how the car behaves so I'm not terribly concerned about that stuff -- I feel that I can judge when it's appropriate and safe to shut the engine off. My primary concern is how hard it may or may not be on the engine. I get the feeling that dumping the clutch into gear would cause unnecessary wear to certain parts of the drivetrain/transmission/engine/whatever.One of the other techniques was coasting in gear. There is a lot of talk about newer cars having fuel cutoff capabilities that will stop feeding fuel when the car is coasting in gear above a certain threshold. Is there any truth to this in regards to the 2003 Vibe GT? Based on the threads that I've discovered through searching, I'd believe that this is the case. If so, what would that threshold be (1000-1200 RPM is a number that I saw pop up frequently). I hate to bring this up again, I just didn't see a definitive answer. I tried this a little bit while cruising around tonight and noticed that the engine does brake quite a bit (which sounds normal) but I'd hate to be leaving the engine roaring at 3000 RPM while coasting down if it isn't doing any good for fuel economy.The final method was to just coast down in neutral. The engine idles at about 1000 RPM when I do this so it doesn't seem as efficient as shutting the car off completely, but it does seem like it'd be much safer. It would be worthwhile to sacrifice a few MPGs for the sake of improved safety so I've been sticking to this method.I appreciate any help that you guys can offer. I'd like to know more about getting the best fuel economy and wasn't able to find definitive answers through my searches.Thanks!Justin

[KITT222]

What would be best is just an engine kill switch, that kills the engine and nothing more. Since I have an automatic, the best I can do is coast in gear or shift to neutral, which after a good discussion turns out to waste more fuel since you idle higher in N than you do in D. I think ecomodder.com may have tips on that engine kill switch. Many people have done it, and I think that bump-starting does cause more wear and tear. Here's a link to the part in the 65+ efficient mods with the kill switch. http://ecomodder.com/forum/fue...php#8Aero modding will help as well. There is a user there named Tango_charlie. HE was the person who really got me interested in a Vibe in the first place, and he has done a few mods to his Vibe for FE and gets good numbers in return. There is also a member named Weather_spotter who owns a Matrix and averages 45+mpg! Go ahead, and look them up. Both will help you. If you want the basic facts, than the wiki is a helpful tool.

[Kincaid]

Here's a discussion on this topic on the Matrix Owner's website.http://matrixowners.com/index....iling

[tpollauf]

Justin. Here's what works for me and my 2009 Vibe GT 5spd-manual tranny: I'm always anticipating when a light will turn red OR when I'm near the next stop sign. Seeing how we are always in neutral between shifts, it's just second nature to push the clutch down & coast where possible. Especially if I'm not in a hurry (generally the case for me) and no backlog of drivers on my tail behind me. Also I have the ScanGauge II and I love watching the current MPG go from 30 or so up to 200-300 MPG while coasting. Coming down from our new I-280 Veterans skyway bridge, here in Toledo over the Maumee river, at 70MPH I'll sometimes coast close to TWO MILES to the exit that I get off on Obviously this is late at night when nobody is around BUT it really improves my MPG numbers. I would NOT recommend killing the engine unless you are pretty much the only person left on the road. Any sudden need to QUICKLY react to an unforeseen road hazard or something else, could be devastating So keep the engine on as much as possible. My 2.4L idles arounf 790 - 800 RPM so maybe drop your idle a bit also. 1000 RPM is a bit high, but maybe the smaller 1.8L that you have needs to be that high ??? That's my take on coasting. Hope it helps a bit ........... Tim

[LarryKingsShoes]

Thanks for the links and tips, guys! I'll experiment with these techniques over the week and keep reading. This could be a good reason to invest in a ScanGauge II. I'm not sure if my idle is high for that engine, or not. I've always attributed it to my car being a GT instead of the base model. I cleaned my MAF sensor about 1,500 miles ago and noticed some improvement at first. Now it doesn't seem to be as noticeable.I haven't been cutting the engine since it's more trouble than it's worth. I could imagine certain situations where it would be practical but those are few and far between. Rolling in neutral is much easier and doesn't seem to be that much more inefficient.

[djkeev]

I am sure you are aware but some States outlaw the practive of coasting and not being in gear.

[LarryKingsShoes]

There are signs posted in most of the cities in Iowa (those that I travel through, at least) that say that an engine brake ordinance is enforced. I think that's more about excessive noise but I'll look into it. Coasting in neutral is much quieter so hopefully it's legal in Iowa. I had wondered about coasting in gear since it would be louder but I never thought too hard about it.Thanks for the reminder! I'm going to look that up so I don't get ticketed. It seems like it'd be hard to get caught doing that but one ticket would quickly undo any money saved on fuel.--It seems that coasting in neutral may be illegal in Iowa after all. Bummer. I can see why it would be frowned upon for safety reasons but I only do it when I'm alone on the road anyway. I don't like following inconsistent drivers so I try to avoid being one if someone's behind me.

[Kincaid]

"Engine brake" should refer to the compression brake used on big rigs, not passenger vehicles. They are called "jake brakes" around here, usually used by the log trucks to save their brakes from overuse, and are VERY loud indeed.As for coasting yourself and it being against the law, far be it from me to suggest you break any law, even if it is very doubtful that the police would ever know or ticket someone for it.I checked out Matrix Owners (that link above) and someone there stated the fuel cut off is not 100% complete when coasting, even though it kicks in above 1100 rpm. Someone else had a Scanguage II hooked up (as I see Tim does as well) as they drove and reported that coasting in gear downhill was something like 150mpg (on the "instantaneous" reading) and that coasting out of gear was about 250mpg.I coast out of gear all the time.

[Kincaid]

So, for the last tank of gas or maybe two, I've practiced this hypermiling technique of coasting out of gear. I'm getting more in the habit as time goes on. I expected some improvement in my mpg.Just checked today as I've almost always achieved 25 mpg or more. I was excited to see how much it would improve.Last two tanks were 24.7 and 24.4 mpg. I know I did have to ferry a daughter back and forth to play practice/performance so that was a bunch of extra stop and go go go. We'll see what the next tank does. The last prior fill up netted me 25.5 mpg.

[Water boy]

ScanGaugeII On my '03 van the mpg goes to 999 at fuel shutoff. I did have the 'puter custom programed a while back to enhance the shutoff table. As well as the trans fluid pressure and tweeked the trans upshifting table. Don't remember what else.I would never shut the engine off just to gain a few points in mpg. Way un-safe IMO.When I had a manual trans I always just pushed the stick out of gear to coast when it was safe to do. Holding in the clutch does put some strain on parts.Remember ... safety first. Getting damaged just to get 2.38492036 more mpg is not worth it.

[Kincaid]

agreed on all points. I'd never coast without the engine on, though a few times on a long downhill that was stop and go (like 4-8 cars getting thru a light every time) I have shut it off because I'm only rolling a very short distance and it takes 10 minutes to get down the hill in those situations.

[djkeev]

Quote, originally posted by Kincaid »Just checked today as I've almost always achieved 25 mpg or more. I was excited to see how much it would improve.Last two tanks were 24.7 and 24.4 mpg. I know I did have to ferry a daughter back and forth to play practice/performance so that was a bunch of extra stop and go go go. We'll see what the next tank does. The last prior fill up netted me 25.5 mpg.Are you saying you used to get 25.5 MPG but with the hypermileage driving you are now getting down in the 24's???Dave

[Kincaid]

Yes. But, there may have been some aggressive driving that offset that. I am looking forward to this next tank to see how it does.

[Applejuice]

This probably isn't helpful (you should probably listen to Kitt222 and the others) But when in doubt....booster jets!

[Kincaid]

Just had my latest fill up and got a very average 25.5 mpg. I am at a loss.

[Kincaid]

Strange! Despite feeling like I was driving kind of aggressively for a lot of my miles, and two days of bad traffic jams, I got 26.5 mpg on the last tank.