A little mileage experiment

[w261w261]

I've had my SE-i for 6 1/2 years now (time flies). Occasionally I check the mileage, which is almost always between 25-26 mpg (30 -31 on a trip). I live in suburban CT, with a Parkway and I-95, although most of my driving is done on local streets or two lane state highways. I live in a town that has almost no stores, consequently, it's a 9 mile drive to the next town to buy almost anything. The terrain is small hilly, the traffic is usually light. Miles on the car: 205k.

I thought I would try to see how much I can increase my mileage, without being an impediment to other traffic, and without driving much slower than I do now. Other than the usual techniques (no hot starts, no 85mph on Parkway, etc), I'm going to try to coast (in neutral) whenever possible going down a hill or coming to a stop sign. If I don't have to worry about other traffic, it is sometimes possible to go a mile or more that way.

I am only going to do this for one tank, as I don't think I could stand it longer. In fact, I don't know if I can make it that far, but I'm going to try. The question for you guys is: what's your estimate of how much higher I can get my mileage?

[turabaka]

That's already pretty good gas milage. I'd guess not too much higher. I get about that in city, and little higher on the highway, but that's because I'm carbed. I'm interested to hear how good you can get it though.

[russiankid]

I doubt you will get much higher. Run some fuel system cleaner through, it improved my mileage by about 1-2miles depending on my driving conditions.

P.S. I am carbed as well and I get the same in the city but 37mpg on the highway.

[2oodoor]

without changing anything on the car? I would say 32 playing grannyfoot :)
If you fine tuned your car, added some 15 inch light alloys, weight reduction, some BG44k in the tank, a fresh 4 wheel alignment... I would say 35 average, 40 highway. Which is what I get with my 86 DX not grannyfooting but not taching much over 3200 rpm either.

[russiankid]

without changing anything on the car? I would say 32 playing grannyfoot :)
If you fine tuned your car, added some 15 inch light alloys, weight reduction, some BG44k in the tank, a fresh 4 wheel alignment... I would say 35 average, 40 highway. Which is what I get with my 86 DX not grannyfooting but not taching much over 3200 rpm either.

I average 30mpg with revving it to 5k at times:wave:

[Oldblueaccord]

Well my story. In 99 i got laid off from work so I took sometime and went to college etc. I tried about 3 tanks never going over 55 mph taking off slow etc. I never saw any differance. Maybe .5 mpg more but not on every tank. Mines and 88 lxi 5 speed. At the time I still ran 185/60/ 14. I think I was getting about 27 mpg.

Now just a few weeks ago I got an all time high for myself mixed city and highway of 30 mpg. funny about it besides I'm mixing E-85 and 87 octane I went up to the dragons tail and drove like a wild man but the speeds were slow. Thats with 205/50/15 tires.

Something about slow speeds our cars do really well mpg at least mine does or more then you would think.

anyway thats my thoughts on it.Good luck and dont get run over up there.


wp

[Hauntd ca3]

dont slip it to neutral coming up to lights
most efi cars will just about completely kill the fuel when you lift off and the mixture goes a bit lean, just enuf to keep it running usually
when you slip into neutral it reverts back to idle programming which a bit on the rich side so will use more gas than just lifting off

[Dr_Snooz]

I predict zero to a negative effect on your MPG.

Good luck though.

[frantik]

dont slip it to neutral coming up to lights
most efi cars will just about completely kill the fuel when you lift off and the mixture goes a bit lean, just enuf to keep it running usually
when you slip into neutral it reverts back to idle programming which a bit on the rich side so will use more gas than just lifting off

yeah in general it will take more gas to turn the crank in neutral than if the tires are turning it

[MessyHonda]

just keep it in 5th gear...i been doing alot of driving and its nice to see when my tank goes over 300

[w261w261]

dont slip it to neutral coming up to lights
most efi cars will just about completely kill the fuel when you lift off and the mixture goes a bit lean, just enuf to keep it running usually
when you slip into neutral it reverts back to idle programming which a bit on the rich side so will use more gas than just lifting off

That makes sense, as far as it goes. Except that the car doesn't go near as far in gear as it does in neutral. Near my home, there's a road that's about a mile long, with a 1/4 mile moderate downhill (this is New England, not much going on in the hill department), followed by a 1/4 mile flat, followed by a 90 degree turn with rough pavement, then another 90 degree turn 100 feet later, then an almost-flat but actually very mild uphill to the light.

Starting at zero and neutral at the top, and gradually building to probably 50+ at the bottom, I must brake for the first turn (I can only do this at night, as they're blind), and then run til I stop by an old farmhouse. I've never tried to do this in gear, but I'm sure it would result in nowhere near the final distance. When I ultimately stopped, I'd have to use more gas to get going again and finally reach the farmhouse. I think in this case neutral would be the better choice.

Anyway, it's an interesting subject. I'm going to try it next time I fill up. My personal problem will be whether I can do this for over 200 miles. Once or twice is fun, a whole week or so might be a drag.

Thanks for the comments.

[markmdz89hatch]

Don't worry, if I happen to see an SE-i on my way home, and it's going painfully slow, I'll be sure to help you along. (btw. I'll be the one in the silver Protege.)

Anyway, I tried this on the same roads (literally) with my Protege. Although mine's a stick, I was much less agressive than usual behind the wheel, and did notice a jump from about 29 to 30-31 mpg. I'm guessing you'll notice a very slight increase in mpg, but not enough to justify driving like that regularly.

Let us know how it works out for you. ..and when/if you run outta gas at the tail end of your experiment, give me a shout on the cell (if you get service in those roads (i know I don't)). I'll make sure I keep an emergency gallon in my trunk for at least the next 2 weeks just incase. lol.

[evil88accordLX]

ill try to keep this as simple so as not to confuse the hell out of everyone. lets say at idle the car gets 100MPG. it averages 25MPG. the tank is 15 gallons. (remember, simple numbers, so dont tell me im wrong because those arent correct for a 3gee). you drive in neutral for 1 mile. thats a 400% increase in MPG for 1/25th of that gallon, or 1/350th of the tank (25 x 15 = 350). thats not much at all at .0028%. to increase the whole entire MPG for the car by 1 to 26MPG or 390 miles a tank, you need to take both variables in account in a single equasion: 25*x1 + 100*x2 = 390 (25+1*15). dont ask me to explain it, i dont have the time, but essentially the end result would be approximately .2 gallons or 20 miles a tank of coasting to go from 25MPG to 26MPG using the figures above. and who has enough empty roads and straightaways for all that. try that in Arkansas and some redneck in a big ass truck will run you over......

[Nafs Asdf]

Umm, wouldn't you get 0 MPG in neutral? ;) As you're consuming an infinite number of gas but going nowhere.

To get a "neutral mpg" you need to factor in how much gas the car uses while idling per minute (or second/hour/week). Then Calculate the distance traveled in neutral at any given speed. The higher the speed, the better mileage you would get in neutral.

Of course don't EFI engines cut off the fuel supply all together when motor breaking? So if you got EFI and a 5-speed, just put into 5th instead of neutral.

[Hauntd ca3]

jaguar used to completely kill the fuel when engine braking i just found out
and these days most cars are reducing fueling to the absolute minimum as i said earlier, not only for economy reasons but for emisions as well
especially with newer lean burn motors
we all know that thre are a milion variables to take into account when trying to get the best out of our tank of gas
terrain,traffic,altitude and the way we use the good old right foot
dont make the motor labour to much and be easy on the gas pedal and you'll be surprised how much you can get out of a tank
I do all my driving to the hi way and get 38/40 mpg from my 5g sir auto being easy on the gas aand being smooth where my wife in her 323 sp20 gets 35 at best on the same trip.
drive smoothly and dont be aggressive on the loud pedal and you'll get good mileage
always used to get 30mpg in town and 35/36 on the highway in my 3g and still kept up with traffic

[evil88accordLX]

Umm, wouldn't you get 0 MPG in neutral? ;) As you're consuming an infinite number of gas but going nowhere.

To get a "neutral mpg" you need to factor in how much gas the car uses while idling per minute (or second/hour/week). Then Calculate the distance traveled in neutral at any given speed. The higher the speed, the better mileage you would get in neutral.

Of course don't EFI engines cut off the fuel supply all together when motor breaking? So if you got EFI and a 5-speed, just put into 5th instead of neutral.

as i stated, im trying to keep it as simple as possible. there are already multiple factors involved in the equasion, and adding time to the equasion just makes it even more complicated. and if you have ever been in a car with an active digital gas gauge, you will notice that even at idle it reads miles per GALLON.

[w261w261]

There are a lot of variables, and this would be no way to drive, that's for sure. It's just an experiment. But I think that the idle gal/hr is way less than driving, more than 4x less, as in the previous post. And I think the coasting part of it would be more than 5% of the total. But maybe not, I'll see.

[Nafs Asdf]

as i stated, im trying to keep it as simple as possible. there are already multiple factors involved in the equasion, and adding time to the equasion just makes it even more complicated. and if you have ever been in a car with an active digital gas gauge, you will notice that even at idle it reads miles per GALLON.

The one car I can remember seing a digital gas gauge in read litres/hour when idling.

If you wan't to calculate your mileage when rolling the car down a hill in neutral for example, you have to include all the necessary factors. Sure, simplify it all you want but you still can't leave out stuff.

[Oldblueaccord]

have you tried the Acetone? Thats painless.

wp

[thegreatdane]

All fuel injected cars cuts off fuel when you are rolling in gear above the idle rpm area.

I recently changed my driving pattern to be more fuel efficient, and I've experienced a very noticable improvement.

Tips are; accellerate with minimum amount of throttle, drive slower/follow the speedlimits, whenever you come to a stop or just need to brake always leave it in gear, driving down steep hills leave it in gear also and let off the gas, change your air filter/regular tuneup.
Coasting in neutral only makes a minor difference and probably only if you can keep it rolling over a long distance.

[evil88accordLX]

The one car I can remember seing a digital gas gauge in read litres/hour when idling.

If you wan't to calculate your mileage when rolling the car down a hill in neutral for example, you have to include all the necessary factors. Sure, simplify it all you want but you still can't leave out stuff.

if the car is rolling, it is not at rest, thus movement was taken into consideration for 1 mile. in turn, the distance in the equasion is one mile in neutral, thus lending itself to a distance variable. and the distance is applied to the fuel and its normal consumption for one gallon, or 1/25th of that gallon. distance is the variable, not time.

lexus IS300 and chevy colbalt read in miles per gallon, even at idle and not moving. those 2 i am sure about.......

[Nafs Asdf]

Of course time needs to be taken into account. If you're rolling the car in neutral you will be consuming less fuel by traveling a distance in 1 minute than you would if you were traveling the same distance in 2 minutes.

Edit: And the gauges might read miles per gallon, but you tell me. How accurate is that? ;)
The car I've seen it in was a Volkswagen Bora I drove in driving school.

[evil88accordLX]

look, im not trying to argue values or mathematics here, all im trying to say is it is possible but improbable to acheive an overall significant increase in gas mileage just by coasting. it can be done, yes, but who has all that free room for so much coasting? i sure dont, traffic here sucks.