Gas Saving Tips

[OEM_SI]

Originally Posted by Johnbro

in gear not touching the gas = no gas into the cylinders
neutral=car has to give gas to idle=more gas

Check when you in gear,.. your rev is higher then in neutral.

When you reving, you engine running faster,...so more gas.

[OEM_SI]

Originally Posted by Johnbro

well i dont coast very often bc im always on the highway with the cruize on, or im slowing down, and i rarely slow down without down shifting bc i let the engine do some extra work to prolong the life of my break pads.

??? brake cost $100,.. gas $35 per tank,... how often do you change your break,...?

[Tastycakes]

OEM_SI It is true tho that fuel get shut off if you put enough negative load on the engine. Its kinda an oxymoron because if you drive in high enough RPM to engine brake your driving at too high of RPMs to get good normal mileage.

I guess if you drive around in 3rd gear all day then yea your gonna save fuel if you enigne brake lol. For those of us that drive at and under 2k RPM then engine braking is kinda pointless at that low RPM.

[Tastycakes]

Since i already did the math, i'll just quote myself from this thread about coasting in neutral vs in gear:

Neutral or in gear, which one use more gas?

Originally Posted by Tastycakes

Ah not this retarded question again.

Yes engines do shut off fuel if you take your foot off the gas and engine brake but you slow down quicker.

If you coast in N you can back off the gas much farther away offsetting the balance.



How to put it, hmm:

Drive normally for 200 feet (use normal gas), engine brake for 200 feet (use no gas)

OR

In neutral and coast for 400 feet (use a tiny bit of gas)

Which one gets you better mileage???


Now lets break it down:

Normal crusing at about 35 MPH uses about 0.6 gallons of fuel per hour (GPH), respectively
Idling uses 0.2 GPH
Engine Braking uses 0.0 GPH

0.6 GPH @ 35 MPH means you use 0.0171 gallons per mile, then divide by 26 (to get 200 feet) you get 0.00657 gallons used
Then engine braking for the next 200 feet costs you 0 gas.

Now the coasting, 0.2 GPH, 0.0057 gallons per mile, divide by 13 (400 feet) you get 0.00438 gallons used.

So what it comes down to, once gain these are just rough calculations:

Driving + Engine braking for 400 feet = 0.00657 gallons
If you Coased in neutral for 400 feet = 0.00438 gallons


I know i didn't factor in time cause i'm too lazy but figure it'll take about the same amount of time to do both then you can also add in if you, say started coasting at 600 feet you save even more fuel. I also didn't add in that you cant engine brake to 0 MPH. You would have to hit the clutch say 10 MPH to keep the engine from stalling using even more fuel.

God i hate you guys, making me have to think and sh1t lol.

And always the best fuel saving way is coasting in N w/ the engine off

[mattellis]

this is a awesome thread.

[daytonaturbo]

One thing I've always wanted to ask the proponents of engine braking is why for the love of god would you want to engine brake to save your brake pads? I mean brake pads are cheap and easy to repair. Engine breaking means your engine is going to be spinning at a higher rpm than idle, which means you are wearing your rings and cylinder bore much much more if you're trying to engine break at 5k versus idling at 800rpm coasting. Plus, when the engine is under a high amount of vacuum when engine decelerating, this places your rods under the greatest amount of stress. The vacuum engine braking stretches your rods the hardest. I see plenty of older hondas around here puking smoke out the exhaust from worn rings/cylinders. Brake pads are cheap, engines, not so much. My $.02 anyway.

[Barry]

Originally Posted by NEMESIS_2006

i always pop the gear in neutral on a downhill. does this have any benefit?

Originally Posted by jasongg06

IMO it does, I do that once in awhile and i think it saves gas, but i've heard that it isn't that great for your transmission. I also know that when the hill ends, and you put it back in gear, the engine revs up, so you didnt' really save any gas.

Actually its worse for gas mileage then if you left it in gear. When you are in gear your momentum going down the hill is turning the wheels and turning the crank, but your throttle plate is closed so you aren't using any gas. When you shift into neutral your car needs to keep the engine turning by using fuel.

Ps dumbest quote of the link is:

Avoid Excessive Idling

Idling gets 0 miles per gallon. Cars with larger engines typically waste more gas at idle than do cars with smaller engines.

No kidding its 0 mpg cause your not going anywhere but thats not actual consumption.

[Barry]

Originally Posted by OEM_SI

Check when you in gear,.. your rev is higher then in neutral.

When you reving, you engine running faster,...so more gas.

OK you just totally missed what he said but ok why don't you re read what he wrote.

[tda1337]

Originally Posted by black07coupe

wow still getting shit gas mileage. last tank was 22, this one was 24... i dont drive it THAT hard jesus.

sorry, saw this and got a kick
ur from friggen boston, what do u know about driving slow?
trust me, ive burned 2 clutches in boston and plenty of brake pads because people around there CANT drive
even my gfs teachers (in waltham) know that people in MA are MUCH worse drivers on ave than those from CT
they all drive AUTOs for one and double footed (gas and brake at the same time... wtf???) not to mention dont know wat a signal is haha
or road rules at all for that matter

[tda1337]

Originally Posted by Barry

Actually its worse for gas mileage then if you left it in gear. When you are in gear your momentum going down the hill is turning the wheels and turning the crank, but your throttle plate is closed so you aren't using any gas. When you shift into neutral your car needs to keep the engine turning by using fuel.

Ps dumbest quote of the link is:


No kidding its 0 mpg cause your not going anywhere but thats not actual consumption.

actually, gas is still being pulled thru the line by the vacuum, and as proved by some of the guys, it uses more GPH in gear than in neutral above 35 mph
personally, driving in gear has costed me upwards of 3mpg (VERY hilly environment in the new england area) whereas i can accelerate down hill in neutral and use WAY less gas

[DBFIU]

Originally Posted by Survivor

I sometimes coast in neutral and get good gas mileage. I think I'll pop over to the Discovery channel website and make a suggestion for Jamie on Mythbusters to see if he can get to the bottom of this one.

I don't think this will work. It doesn't involve blowing sh1t up or making the redhead kari get wet, so they won't air it.

Too bad.

- Dan

[Mutato]

I would think any gas savings by coasting, if it's true, would be offset by increased costs of replacing your brakes more often than downshifting. I hardly ever have to replace brakes versus people with auto trannys. They seem to blow through them.

[DBFIU]

I'm surprised why no one has yet to put 2 and 2 together.

Assuming your engines A/F is 17:1 when coasting in gear, indeed it is using less fuel per combustion cycle as opposed to straight idling which has an A/F of around 14.7:1.

What we are failing to realize is that there are 5 times more combustion cycles at 4000 RPM than at 800 RPM idle, so you will naturally use more fuel in gear coasting.

Does that make sense now?

[ForTozs]

It goes to show how close minded people can be. I guess people aren't much different on the internet than they are on the roads. I agree DBFIU, under those assumptions which nobody has given any strong evidence against (and there seems to be good evidence for), it is clear what gives better mileage. What I find even more interesting is that people would rather wear out their engines than their brakes. Also for the non-believers, consider what happens to your speed when you brake with the engine. The deceleration (fuel economy's enemy) is far greater with the engine in gear. If you want to get back to speed, you will have to make up that speed difference (also an enemy of FE) more than if you had just popped it in N for a few seconds with little loss of speed. Also, downshifting can be unsafe since you don't use your brakelights. And Barry, calling 0 mpg at a stop/idle "not consumption" is missing the point (0 mpg is not equal to 0 mpg for two different cars). Fuel is being consumed, and in different amounts. I guess its your point that I'm missing on the "dumbest quote" part. I've heard some dumber ones here. But this is a great thread. Maybe it will help empassion me to be a more patient, fuel-concious driver. Anyway, one thing I've noticed with my AT (Lord I miss my MT) is that if I give a good tap on the brakes before coasting toward a red light, it cuts my RPM down compared to if I let the engine do the work. I've assumed I'm putting the car in neutral by doing this, but I could very well be wrong. Either way, it seems like it should be saving me fuel since I get much lower RPMs this way and coast further.

[Dethred]

I just got 36.8mpg driving in traffic from Williamsburg to Nags Head in my Si. That was with a few "Vtec" runs within the limits of the law, 3 hours of stop and go traffic, and constant speed (limit) adjustments along the way. My car has now reached 5700 miles (in 1.5 months) and its still gaining fuel mileage as the engine "breaks in". I have experimented with my car's fuel economy since day one, and my habits are as follows.

1.) Keep my following distance to 3-4 seconds at any given speed. Drivers ahead always love to bunch up and tap their brakes. Usually those 3-4 seconds of distance allow me to simply engine-brake or avoid braking all together.

2.) When the hill is steep enough, I "engine-brake" until my speed begins to decrease a mph or so. As confirmed by the email from an employee at Scangauge, and by the simple fact that most newer MT cars behave in such a manner, the engine will not consume fuel when it is being rotated by the physical attachment to the wheels (wheels-axles-transmission-flywheel-crank). Fuel is not needed to keep the engine RPM above stall levels, because the 2900lb car is spinning the engine just fine.

3.) Coast in Neutral when coming to a stop. In traffic, I try to predict when there is a stop ahead, and begin to coast well in advance, usually to avoid having to brake.

4.) My Short Ram Intake isn't exactly meant to increase fuel consumption, but I can monitor my throttle usage by simply listening for the hissing sound from the filter. If I avoid that at all costs (unless I want to ) I can get much better fuel mileage. Obviously there is no real physical difference between the lack of that hissing sound and when I hear it, but I think of it as a warning sound for when I am using too much throttle (again, unless I want to ).

5.) Drive as slow as safely possible. I drive 2 hours a day to and from work (100/mi. round trip). I would love to get there as fast as possible, but just dropping from 70mph down to 65mph increases my mpg from about 32mpg up to 35-36mpg. I just sit back, stay in the right lane, set it to cruise, and listen to my classical selection on the XM radio.

Since buying the car I have gotten my wife off my case for having bought a car that requires premium and only is rated for 29mpg Highway.

[DBFIU]

I don't know how you do it, I can't seem to break 29 mpg in my car with very easy driving. Maybe I'm doing something wrong or my car is a freak of nature. I broke my car in right (so many variations of break-in, there is no right in this case).

35 mpg, hell I wish I could get 30.

- Dan

[leonphelpss11]

Originally Posted by DBFIU

I don't know how you do it, I can't seem to break 29 mpg in my car with very easy driving. Maybe I'm doing something wrong or my car is a freak of nature. I broke my car in right (so many variations of break-in, there is no right in this case).

35 mpg, hell I wish I could get 30.

- Dan

I'm hitting around 22mpg with no ac and mostly city and maybe one time a day gas mashing on the highway. My tires also had 3 nails sticking in like each of them and losing pressure at various rates. I just changed my tires, used seafoam, bout to chg out oil and tranny fluid.

I don't really do that much of a spirited driving, maybe vtec like once every 3 days. I'm not really sure why im getting such crap. When i mash on the gas, its only in 3rd gear and I shift at 5,000 and then go to 4th then 6th.

[tda1337]

air filter, check it
i can get up to 45.24 mpg (top so far) but thats on long trips, ave with lots of redlines and decent driving is 30-36 (34mpg regular with mix slow/fast driving)

lists of musts:
if you drive auto - you must be sure you dont go above 3500 RPM
if you drive manual - dont go above 2500, seems hard, but if you are going for MPG go for under 2000, thats what i do when i TRY to get great mpg
if your trips are under 10 miles, that doesnt help either
also make sure tire pressure is above 32 at MINIMUM
AIR FILTER! get it cleaned ASAP!
Tire ALIGNMENT!
switch to rims if you have steelies, they are lighter
accelerate down hill, slow down up hill, aka pedal (throttle) NEVER past 25%
CLOSE your windows and do the A/C hack to allow use of the front window defogger without the A/C kicking in (if you dont believe me that it is on, listen for the click of the compressor lol, do it at idle and play with it)
MOONROOF CLOSED!

and for manual drivers NEUTRAL!!!
trust me on that! if you think that your gonna get in an accident cause your in neutral... new flash, YOU HAVE ABS, it allows for steering under heavy braking and your stopping power when ABS is involved has nothing to do with your engine. Unfortunately it negates an engine holding you back as well... sorry to those who think they are stopping fast! if you want to stop fast, Go with Michelin's!
Still have yet to see an accident where the dude was in neutral! (may be diff for auto users in rain conditions as comming off of neutral automatically applies horsepower to the wheels and can cause problems) whereas a manual thats dependent on your use of the clutch

Try the tricks above from a tried and trued Hypermiller!!!

[leonphelpss11]

Originally Posted by tda1337

air filter, check it
i can get up to 45.24 mpg (top so far) but thats on long trips, ave with lots of redlines and decent driving is 30-36 (34mpg regular with mix slow/fast driving)

lists of musts:
if you drive auto - you must be sure you dont go above 3500 RPM
if you drive manual - dont go above 2500, seems hard, but if you are going for MPG go for under 2000, thats what i do when i TRY to get great mpg
if your trips are under 10 miles, that doesnt help either
also make sure tire pressure is above 32 at MINIMUM
AIR FILTER! get it cleaned ASAP!
Tire ALIGNMENT!
switch to rims if you have steelies, they are lighter
accelerate down hill, slow down up hill, aka pedal (throttle) NEVER past 25%
CLOSE your windows and do the A/C hack to allow use of the front window defogger without the A/C kicking in (if you dont believe me that it is on, listen for the click of the compressor lol, do it at idle and play with it)
MOONROOF CLOSED!

and for manual drivers NEUTRAL!!!
trust me on that! if you think that your gonna get in an accident cause your in neutral... new flash, YOU HAVE ABS, it allows for steering under heavy braking and your stopping power when ABS is involved has nothing to do with your engine. Unfortunately it negates an engine holding you back as well... sorry to those who think they are stopping fast! if you want to stop fast, Go with Michelin's!
Still have yet to see an accident where the dude was in neutral! (may be diff for auto users in rain conditions as comming off of neutral automatically applies horsepower to the wheels and can cause problems) whereas a manual thats dependent on your use of the clutch

Try the tricks above from a tried and trued Hypermiller!!!

I always thought it was 2500-3000 was the perfect rpm range for manual??? What do you mean about the ac hack? I'm not really understanding that part??

Also I thought Honda recommends 27-30 psi for the tires??

[JeShUa]

Just got my best MPG EVER. Must be the pass seat delete. GGNORE.