Do you "coast"?

[Flatland2D]

When going downhill do you put the car in nuetral and coast until you begin to lose speed again? I usually do it if I remember, and I'm more likely to do it on long trips. Each coast for me can last anywhere from 0.1 miles to 0.5 miles. They will really start adding up over the course of a tank and you should be getting a few more miles out of it. The only drawback is increased clutch wear and you are using more gas in the time it takes the engine to get back up to speed than if it cruised at that speed for the same time. It only takes a second to whip up the rpm's though and a coast lasts a lot longer than that so you still should come out on top.

So how often do you guys do this if at all?

BTW, I've heard this is illegal because you don't have control of the car or something like that (what are the steering wheel and brakes for then?). Anyway, it's not like some cop is ever going to notice or be able to prove you had the engine disengaged. Just wanted to mention this as a precaution though.

[Matt Timion]

I actually coast most of the time... even during city driving. I'll see a red light 500 feet ahead and I'll just throw it into nuetral. I always have enough momentum to make it to the light.

I swear that my coasting all of the time is one of the reasons I get such great gas mileage.

Seriously though, coasting downhill really is the best.

[diamondlarry]

My 1997 Saturn has no power steering so I carry the coasting a bit further. I turn the engine off and coast up to a light then pop the clutch in 4th gear just before I get stopped. You have to turn the key back to run right after the engine dies so the speedometer will register the distance you're travelling with the engine off. I've found that at 50-55 on a contry road I can coast as far as .8 miles and still be going 20-30 when I get to the next stop. Last summer I went a tank without doing this and found that my mileage dropped about 3 mpg.

[SVOboy]

Flatland, when you coast you should put the car into neutral because not only will you save gas but you will have less wear on the clutch. And when I say wear on the clutch, it is not actually the clutch getting worn but the clutch's throwout bearing. I always coast in my mom's camry by putting it in neutral, but since my car is an auto going down hill coasting is messed up by the auto not disengaging the clutch and slowing the car down and blah blah blah, so it is harder and not as efficient, but I still coast in the crx. However, I don't turn the engine off.

[Matt Timion]

Flatland, when you coast you should put the car into neutral because not only will you save gas but you will have less wear on the clutch. And when I say wear on the clutch, it is not actually the clutch getting worn but the clutch's throwout bearing. I always coast in my mom's camry by putting it in neutral, but since my car is an auto going down hill coasting is messed up by the auto not disengaging the clutch and slowing the car down and blah blah blah, so it is harder and not as efficient, but I still coast in the crx. However, I don't turn the engine off.

Yeah, i might actually turn the car off when I coast if I didn't have power steering. It also seems like such a hassle to be turning the key, and popping the clutch, and all of that other stuff. What would be really neat is if we could make a button to go on top of the gear shifter that turns the car off and on. You just throw it into nuetral, push the button and go. Push it again to start er back up.

I'm also pretty sure that when I get the new LRR tires I will be able to cost much longer, considering the lower amount of friction on the road.

[SVOboy]

I am thinking for that you would get the zemco fuelsaver type device and add another rigging up on it for a button to shut down the engine but not require ignition again, but hell if I know how it works, just that it does.

[Flatland2D]

Flatland, when you coast you should put the car into neutral because not only will you save gas but you will have less wear on the clutch. And when I say wear on the clutch, it is not actually the clutch getting worn but the clutch's throwout bearing. I always coast in my mom's camry by putting it in neutral, but since my car is an auto going down hill coasting is messed up by the auto not disengaging the clutch and slowing the car down and blah blah blah, so it is harder and not as efficient, but I still coast in the crx. However, I don't turn the engine off.

That's what I meant - putting the car in neutral. As far as wear of the clutch, every gear change will wear the clutch a little, but they last for so long I don't think it's really an issue. I would be hesistant of popping the clutch everytime I coast. That's got to be really hard on your transmission. But to each his own.

How about this idea. Maybe it's worth being another topic but I'll stick it here for now. Body kits could play a big factor in coasting ability and general fuel economy. A well designed kit (from a wind resistence perspective) ought to have less drag. A good feature is a bottom lip that helps reduce drag generated from under the car. Here's another pic of my car as an example.

<img src="http://www.morlinos.com/delsol/delsol10.jpg">

The bottom lip might help with under-the-car drag, but behind the wire screen is metal reinforcement that's not very aerodynamic. Maybe air is getting trapped in the cut-outs. The idea might be worth considering if you're already in the market for a body kit, but it wouldn't save you any money if all you're buying it for is less drag. The kit I have costs $850 and theorectically if it gave me 1 or 2 mpg more, it would take a reeeaaaally long time to pay off.

I don't have power steering in my car either. I think they got rid of it when they did the swap (I didn't own it at the time).

[SVOboy]

Haha, more pictures...nice. In any case, I don't pop the clutch, cuz I realize that sucks on the tranny. I want to swap trannies anyway but if I killed it my dad would get mad with all the jokes I make about killing it so I can do the swap sooner. In any case, I've heard conflicting things about body kits. Yes the stuff traps air in front, but also reduction drag under the car is good. Lowering the car is also gooood. What is really the best besides adding crap is somehow venting the back bumper so it doesn't dam air up in there. Also, matt and I have thrown ideas around about making a fiberglass plug for the back wheel wells like the insights have, to reduce drag, but I dunno anyone who can do that.

[Flatland2D]

Haha, Insight wheel well covers would be sweet. I don't know how you'd go about having those made though. Youd certainly be getting a lot of weird stares coming down the road.

In case you want any more pics, <a href="http://www.honda-acura.net/forums/showthread.php?t=198108">here they are</a>. It's a post I made at Honda-Acura.net when I first bought the car.

[SVOboy]

Well, this has strayed from coasting so I'll shut up after this post so people can actually discuss it since it's good. So you should prolly post in the introduction thingy cuz then I can comment away. The rear wheel covers wouldn't be that hard except how to mount them and have them removable, but I think just a few brackets or something, but I dunno crap about fabrication so that's settled on my end.

[Matt Timion]

Fiberglass wheel covers will be a project of mine in a few months (maybe next spring). I first need to do the engine swap, install cruise control, put the new wheels on and do other small modifications like the PCV catch can or maybe the A/C kill switch when accelerating.

Eventually though, I'll get those damn wheel skirts made. Another problem with it though is that the insight rear wheels are considerably inwards (toward the center of the body). On all other cars the wheels stick out. Maybe the trick is to get super small wheels too, which I will NOT do considering I just spent a small fortune on my HX wheels.

[Paul Osborne]

I drive an automatic and am a big time coaster. Heck, I’ll crawl as far as I can and relax while doing it. Part of smart driving is knowing how much gas you need to burn between point A and point B. It’s always interesting to see SUV’s and trucks roar around me so they can get to the red light first. Should I pat them on the rear bumper and congratulate them for winning the race?

Coasting is for relaxation, but hurrying it up breeds anxiety.

Paul Osborne

[SVOboy]

I drive an automatic and am a big time coaster.

But do you only coast coming into lights or other sorts of stops or do you do it when going down hill or other times when you'll be starting back up at relatively the same speed? The thing with my auto is that it always reengages in first gear and then has to fly around to find the right gear and it doesn't like it at all.

[Paul Osborne]

I pretty much coast as much as I can. If I don't need to burn the gas I let up. I'm a very patient driver - I can even rejoice in a traffic jam!

My wife tells me I drive like an old lady. :-D

If I think there is a stop sign up ahead, my foot is already off the gas. Remember, I'm the guy who wrote the book Take Your Foot Off The Gas. ;-)

Paul Osborne

[SVOboy]

This will hurt fuel economy more than it will help it. In an effort to save gas, Honda ECUs turn off the fuel injection if the throttle is closed AND RPMs are higher than a specified amount (900RPM, I think). So if you are cruising down a hill with the car in gear and the throttle closed, the car is burning no gas (provided the engine is spinning faster than the threshhold RPM). If, on the other hand, you put the car in neutral, it has to burn gas just to keep running.

Someone mentioned coasting downhill and someone said they above, I've heard this a lot in specific to honda's, anyone know any solid information or where to get it?

[rh77]

I read somewhere that putting the car in neutral actually uses more fuel -- here's the theory. When you lift your foot off of the gas, you allow the car to remain in vaccum, compression of the engine is used to slow, and minimal fuel is delivered. If you shift to neutral, you're asking the car to use deliver fuel just as if you are idling, which which may be more than allowing compression to slow you down. If you have a manual, the recommendation is to stay in top gear until the engine is about to bog, then shift to neutral, or cut shut the engine down.

RH77

[SVOboy]

That's what I've heard about honda in particular, but talking to drdisco from h-t, he suggested that mehbe the cost of decelleration from engine breaking would mean less time to coast or more need to accelerate after coasting, which might make coasting in neutral a more viable solution.

[rh77]

Over at h-t there's a thread that really tries to figure this out (and really belabors the issue at times)...

http://www.honda-tech.com/zerothread?id=1404584&page=1

Essentially the fuel injection system (including DPFI) pulses to lean out the mix on closed-throttle, whereas the fuel injectors are on full-duty during idle to maintain a certain RPM. You're correct in the fact that is may slow you down too quickly, so then fuel is to be used to catch back up to traffic, so finding that sweet spot would yield the best economy. This would be much easier on a manual, because my automatic gets all confused when I shift to neutral down a hill going 55-60, then shift back to D4, which causes some drag and may have negated the whole fuel savings while coasting (basically it seems to go into 3rd then down to 4th).

The best thing to do is to cut the fuel injection entirely when coasting, perhaps? That way you get to keep all that fun safety stuff running(if you have it) like power steering and power brakes.

RH77

[SVOboy]

Power steering psssh...I don't need that. I would like my power brakes back though. Sometime soon I'm going to start experimenting with shutting to car off to coast.

[rh77]

Power steering psssh...I don't need that. I would like my power brakes back though. Sometime soon I'm going to start experimenting with shutting to car off to coast.

I had a '97 Civic DX with no power steering and no A/C. During the summer I lived out in the country and commuted to work about 40 miles away. (This was in Ohio) - out on the back roads, the lack of P/S was great -- you could really feel everything the car was doing in corners (lots of fun). 30-40 mpg, manual trans. What a great college car. Traded it on a '99 Civic Si (best car I had). Then the EVO bug bit me and I treaded into 18 mpg territory. It lasted about a year -- too many glitches in the tranny. Traded it on the TL (no regrets, it was a rush, but I'm over it).

RH77

[diamondlarry]

Power steering psssh...I don't need that. I would like my power brakes back though. Sometime soon I'm going to start experimenting with shutting to car off to coast.

Since I don't have power steering that one isn't an issue for me. As far as power brakes though, I have never noticed a problem with not being able to push the pedal to stop. I think I heard somewhere that if your brake booster is in good shape that it should have enough vacuum to operate the brakes a few times with the engine off.

[SVOboy]

That's true, larry. My brake booster is bad though, which presents the problem for me of coasting with the car off. :-)

[dddon]

hey guys!
for what it may be worth to the "coasters" discussion.. i am driving a minivan that has a mpg meter built in .. and what it reads if i coast in drive is about 30 -40 mpg ... if i put it in neutral it climbs to over 100 mpg if i coast a long way ...
that sez to me that the drag of the tranny on the engine speeds it up an burns more fuel ... so you do get better mpg in neutral ... as far as clutch wear ... i drove a vw bug 100000 miles with the same disk .. remember ..the clutch is there so you can get the car moving .. after that it should not slip unless you step on the gas before it is fully engaged ... i love to drive a stick ... an shift without using the clutch except to stop an start ... most truckers could do it very well , an my son is now learning how since i told him to try it .. he is 51 and sez he will teach his boys how this summer ......... dddon (great grampa too)

[slurp812]

When I am diligent with my coasting, my FE is much better. Its true that my accord shut off injectors when I let off. I felt it going down a steep him in first once. But that also drags down the momentum very quickly. I do however use it when I need to slow down a bit, I just let off. In a few spots, I can coast over a half mile. I have one when taking back roads that goes down a small hill, and the speed is 45. If I am doing about 50 when I start to go down hill, I coast nearly 9/10ths of a mile. Its all straight, so I usually turn it off.

[VetteOwner]

i coast, one of my cars is mechanical spedometer cable so if the cars rolling miles are added, the other has a mechanical odometer but its electronically fed, i dont coast with engine off.

with a manual if you judge the load just right you dont have to press the clutch to disenguage it, get it at that rpm where your not accelerating(startign to go down the hill) letting off the gas so the rpm drops and theres no load on the wheels (as the wheels are starting to turn the engine, hence engine braking) so you can just pull the lever out of gear. you do have to press the clutch to put it back in gear, and rev match the engine to tranny speed to save clutch wear.

by that i mean know what rpm your cars at given a speed and gear. rev the engine up slightly near that rpm number then release the clutch, saves the clutch even more so its liek you never released it.

heck i belive ive gotten 142k miles on the stock clutch (dont know for sure but weve never changed it in 40 k miles and the guy before us never changed it)

[CO ZX2]

i coast, one of my cars is mechanical spedometer cable so if the cars rolling miles are added, the other has a mechanical odometer but its electronically fed, i dont coast with engine off.

Electric speedometers generally will register OK with engine-off coasting if you return the key switch to on position after killing the engine.

[acetone marty]

Hi Guys i have found the same results as some of you i drive a ford focus 2000 dohc and i coast in neutral as much as possible. My scangauge will hit 90 to 100 mpg coasting in gear like up to a stop light, but if i put it in neutral i have hit over 200mpg. If i am going down a long hill on the highway i will go into neutral let it run out even if it goes over the speed limit watch the speedo and coast until it drops to my cruise setting and hit resume doesnt require any fuel to get upto speed.I have found with my scangauge that if i coast going down i can usually get back what extra fuel i used to go up the hill.

[R.I.D.E.]

We noticed injectors shutting off on 1981 Nissan 280Zs(first oxygen sensor versions), when the throttle was released when revving the engine with a stethoscope listening to the injectors. You can use a long screwdriver placed on the body of the injector. You can hear it ticking and it should shut off when the throttle is released.

This eliminates fuel delivery when engine vacuum is highest and allows the elimination of air injection systems to control the unburned hydrocarbon peaks that occur if you allow fuel to be delivered when the throttle is released.

regards
gary