Couple of tips on fue efficiency

[MN]

Also always try to preserve momentum, it's that initial inertia that
kills the MPG's in the City.

This is the absolute number one as it directly relates to producing
force needed to accelerrate mass.

Friction issues are secondary but also very very important.

Starting with good, proper octane grade, fuel in the fuel tank
preferably with some lubricant added such as Marvel Mystery
Oil, all below can and do significantly affect fuel economy:

1. Fuel lines that are not rusted, fuel filter that is not clogged
(change either).
2. Fuel injectors atomizing fuel properly for better, more efficient
fuel burn (injector cleaning, or replacement).
3. Good spark plugs make a big difference, especially if
worn out (change frequently as TOP (!) performance
degrades quickly with most spark plugs).
3. Engine oil of light weight, preferably synthetic for reduced
engine friction, likewise change regularly.
4. EGR and exhaust system working properly so excessive
obstruction does not exists here.
5. Similarly air delivery system, properly working Idle Air
control valve, clean air filter is a must (change frequently,
especially in dusty areas).
6. Synthetic oil of proper weight, preferably on the light side,
in all manual/auto transmissions, and particularly differentials.
7. Tires properly inflated (slight bias for overinflating).
8. Windows rolled up completely to reduce any drag.
9. Car surface clean, heavily waxed and well polished to reduce
surface friction (especially helpful on long distance higher
speed trips).

All the above plus proper driving technique will help reduce fuel
consumption significantly. One not recommended practice, and
in fact illegal in many places, is coasting out of gear, that is in
neutral. This can help save some fuel but is very, I repeat, very
dangerous, and not cost effective as much more wear is put on
the brakes.

Happy Subaru motoring everyone,

MN

 

[MN]

This is the absolute number one as it directly relates to producing
force needed to accelerrate mass.

Friction issues are secondary but also very very important.

Starting with good, proper octane grade, fuel in the fuel tank
preferably with some lubricant added such as Marvel Mystery
Oil, all below can and do significantly affect fuel economy:

1. Fuel lines that are not rusted, fuel filter that is not clogged
(change either).
2. Fuel injectors atomizing fuel properly for better, more efficient
fuel burn (injector cleaning, or replacement).
3. Good spark plugs make a big difference, especially if
worn out (change frequently as TOP (!) performance
degrades quickly with most spark plugs).
3. Engine oil of light weight, preferably synthetic for reduced
engine friction, likewise change regularly.
4. EGR and exhaust system working properly so excessive
obstruction does not exists here.
5. Similarly air delivery system, properly working Idle Air
control valve, clean air filter is a must (change frequently,
especially in dusty areas).
6. Synthetic oil of proper weight, preferably on the light side,
in all manual/auto transmissions, and particularly differentials.
7. Tires properly inflated (slight bias for overinflating).
8. Windows rolled up completely to reduce any drag.
9. Car surface clean, heavily waxed and well polished to reduce
surface friction (especially helpful on long distance higher
speed trips).

I new there were ten things, forgot to mention the O2 (oxygen)
sensor. A properly working one can save fuel big time!
Probably O2 sensor should be somewhere at the very top of
the list.

Anything else, gang?

MN

 

[Grolsch]

Good to see that folks out there are really become conscious of fuel, fuel
consumption and consumption in general. I hope this new level of awareness
becomes more global. I'm sure Subaru drivers, in general, are slightly ahead
of the curve in this regard.

 

[Dave - Dave.net.nz]

Good to see that folks out there are really become conscious of fuel, fuel
consumption and consumption in general. I hope this new level of awareness
becomes more global. I'm sure Subaru drivers, in general, are slightly ahead
of the curve in this regard.

if only because we drive "thirsty" cars... or is it because we have lead
feet?

 

[Andy Leszczynski]

What about limiting A/C usage?

 

[Paul]

Good to see that folks out there are really become conscious of fuel, fuel
consumption and consumption in general. I hope this new level of awareness
becomes more global. I'm sure Subaru drivers, in general, are slightly ahead
of the curve in this regard.

honestly though i think Subaru is a little behind the curve on making
cars with better fuel economy. Always here about toyota, honda, gm,
ford, chrysler, and some others about fuel economy but not subaru. i
know they have that electric hyrbid but still not really a great choice.
yeh subaru owners in general tend to care about the environment but
subaru itself needs to do alot more work. just my opinion.

Paul


--
Paul Johnson
Graduate Student - Mechanical Engineering
University of Florida - Gainesville, Fl
http://plaza.ufl.edu/redboots

Reclaim Your Inbox!
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[Paul]

honestly though i think Subaru is a little behind the curve on making
cars with better fuel economy. Always here about toyota, honda, gm,
ford, chrysler, and some others about fuel economy but not subaru. i
know they have that electric hyrbid but still not really a great choice.
yeh subaru owners in general tend to care about the environment but
subaru itself needs to do alot more work. just my opinion.

Paul

i stand a little corrected.....
http://www.edmunds.com/insideline/do/News/articleId=106928

Paul

 

[MN]

What about limiting A/C usage?

Yup. On the limiting side, I'd suggest if possible limiting
very high speed driving, AC use, prolonged idling, and
weight carried in the trunk.

The AC thing is a bit tricky as not all cars seem to respond
equally. My old Corsica 2.8LV6 uses only slightly
more gas when the AC is running, but the 2.2L Subaru
seems to use a lot. I also have a 1.5L Hyundai that gulps
gas like crazy with the AC on. I think that the bigger the
engine the less fuel is needed to run the AC (?). Why, how
I don't know. Maybe its just a perception as a big engine
uses more gas to begin with.

MN

 

[MN]

Yup. On the limiting side, I'd suggest if possible limiting
very high speed driving, AC use, prolonged idling, and
weight carried in the trunk.

The AC thing is a bit tricky as not all cars seem to respond
equally. My old Corsica 2.8LV6 uses only slightly
more gas when the AC is running, but the 2.2L Subaru
seems to use a lot. I also have a 1.5L Hyundai that gulps
gas like crazy with the AC on. I think that the bigger the
engine the less fuel is needed to run the AC (?). Why, how
I don't know. Maybe its just a perception as a big engine
uses more gas to begin with.

On the AC note, now may be a perfect time to get window
tinting. Gas prices are not going down any time soon, while
many tinting places are offering Fall discounts.

MN

 

[Mike Lloyd]

CNN had a report on A/C vs. fuel economy not too long ago. The test results
(same car, same driving conditions, same weather and driver) revealed that
A/C usage hampered fuel economy at low speeds, and thus an open window would
be an economical alternative. On the other hand, they found that the A/C
system yielded BETTER mileage at highway speeds versus an open window due to
the aerodynamic effects of an open window. These results were A/C verses
windows, obviously using no A/C and the vent only will save gas over both,
since you retain the best aerodynamic efficiency and reduce the typical 5 hp
gas consumption required by the A/C system.

Mike

 

[Doug Warner]

CNN had a report on A/C vs. fuel economy not too long ago. The test results
(same car, same driving conditions, same weather and driver) revealed that
A/C usage hampered fuel economy at low speeds, and thus an open window would
be an economical alternative. On the other hand, they found that the A/C
system yielded BETTER mileage at highway speeds versus an open window due to
the aerodynamic effects of an open window. These results were A/C verses
windows, obviously using no A/C and the vent only will save gas over both,
since you retain the best aerodynamic efficiency and reduce the typical 5 hp
gas consumption required by the A/C system.

I do it this way for other reasons. When it's not too hot to tolerate
it, I open the windows as soon as I get in, and leave then open until
I get up to highway speeds. Then, due to excessive noise, or
discomfort from the buffeting, I'll reluctantly turn on the AC.

One thing I just don't understand is people who get in their cars on a
perfect, dry 80 degree day, and drive off with the windows closed and
AC on full blast..

--

 

[Paul B]

I unplugged the DRL Resistor, deactivating the DRL's
and noticed an immediate fuel consumption improvement.

It's the SILVER colored rectangular block mounted
on the passenger side strut that has TWO wires
comming out of it. (DO NOT get it mixed up with
the one with FOUR wires - leave that one alone)

Unplug the two-wire connector. Headlight will
work normally apart from DRL which is a waste of
time on a car anyway. DRL is needed for Motorcycles
with a low distance visual profile, not a bulbous 4000
pound subaru wagon.

 

[Cam Penner]

I unplugged the DRL Resistor, deactivating the DRL's
and noticed an immediate fuel consumption improvement.

What was the difference? How many MPG, measured in which
way?

 

[Paul B]

What was the difference? How many MPG, measured in which
way?

2 to 3 MPG (less pull on the alternator) in city driving
It ain't much but every bit helps!

 

[Cam Penner]

2 to 3 MPG (less pull on the alternator) in city driving
It ain't much but every bit helps!

How did you measure this? Torque required to turn the
alternator at idle? At driving RPM? Single tank milage?
Multiple tank milage?

 

[Cixcos]

Pls tell where this resistor is located. Or is it a fuse? TIA!

Ben

 

[Dave Morrison]

What was the difference? How many MPG, measured in which
way?

That would be an interesting number to see.

How about the theoretical numbers-

DRLs are typically about 25w. Assume that
two of them require about 100w to run with dismal
50% efficiency of the alternator.

According to some quick research, a U.S. gallon of gas
contains about 44 Megajoules, and the gas engine is about
25% efficient.

So a car that gets 30 mpg at 60 mph is using 2 gallons
per hour, or 352 Megajoules per hour.

In that hour, the headlights have consumed 0.36 Megajoules.
(100 * 3600 seconds)

So the DRLs are using 0.1% of the engine's consumption.

Disconnecting the DRLs should see an improvement upwards
to 30.03 mpg from 30.00.

 

[Cixcos]

Found out message with location further down the thread. Pls disregard.
I'll try disabling the DRW and see how it works. Gas is way too
expensive these days, and I don't see it going down anytime soon.

 

[Don]

That would be an interesting number to see.

How about the theoretical numbers-

DRLs are typically about 25w. Assume that
two of them require about 100w to run with dismal
50% efficiency of the alternator.

According to some quick research, a U.S. gallon of gas
contains about 44 Megajoules, and the gas engine is about
25% efficient.

So a car that gets 30 mpg at 60 mph is using 2 gallons
per hour, or 352 Megajoules per hour.

In that hour, the headlights have consumed 0.36 Megajoules.
(100 * 3600 seconds)

So the DRLs are using 0.1% of the engine's consumption.

Disconnecting the DRLs should see an improvement upwards
to 30.03 mpg from 30.00.

That figure sounds a lot more realistic than his 2-3 mpg. If he had put
..02-.03, he could be believed.

Don D.

 

[Don]

That would be an interesting number to see.

How about the theoretical numbers-

DRLs are typically about 25w. Assume that
two of them require about 100w to run with dismal
50% efficiency of the alternator.

According to some quick research, a U.S. gallon of gas
contains about 44 Megajoules, and the gas engine is about
25% efficient.

So a car that gets 30 mpg at 60 mph is using 2 gallons
per hour, or 352 Megajoules per hour.

In that hour, the headlights have consumed 0.36 Megajoules.
(100 * 3600 seconds)

So the DRLs are using 0.1% of the engine's consumption.

Disconnecting the DRLs should see an improvement upwards
to 30.03 mpg from 30.00.

Also, based on his numbers, he should get about 20 mpg more without the air
conditioner, 6 mpg more when driving during the day without headlights and
5-10 mpg more by not using his radio. 60 mpg sounds about right.

Don D.