2003 Honda Accord 4 cyl gas mileage on the highway

In rec.autos.makers.honda Elmo P. Shagnasty > wrote:
> So you're keeping your throttle at exactly the same position, manually,
> and if you go up or down a hill and your speed changes dramatically, so
> be it?

My Datsun roadster had a manual throttle lock. I'd get to cruising speed,
pull the knob, and there I was... Mechanical Cruise Control.

Same thing for a few bucks on motorcycles, some sort of flip-lock on the
throttle. http://www.rattlebars.com/mtz/invisible.html

On roughly level ground, it worked just fine. A freeway overpass would
knock some speed off, and down the other side would overspeed, but overall
it was a pretty decent thing.

Logically, one might do the same thing with an electronic cruise control.
As my Civic starts up a grade, I have two choices: I can let the cruise
control maintain the speed, including over 5000 RPM, or I can kill the
cruise control. If it's a long grade, I let it run whatever RPM it wants.
If it's a minor grade, I kill it.

If there was some tolerance, allowing the speed to drop, programmed for a
typical overpass, cruise control could be more efficient. People without
cruise control are probably losing speed at that point anyway, so they
would never notice.

--
---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5

On Fri, 09 Sep 2005 18:25:55 -0400, "Elmo P. Shagnasty"
> wrote:

>In article >,
> flobert > wrote:
>
>> >So you're keeping your throttle at exactly the same position, manually,
>> >and if you go up or down a hill and your speed changes dramatically, so
>> >be it?
>>
>> I say up front i ahven't used cruise control in years, except for once
>> last week. My vehicles don't have it, i don't use it. I used it on my
>> wifes work van, a 96 T+C. Before this, my last experiance was with a
>> 03 buick century back in 03 (a rental car).
>
>So you're saying you have very little experience with cruise control.

I'm saying i have limited experiance, but with that, i pay a lot more
attention to what its doing - its not something i take for grated, and
ignore as a backgroud part of driving'

>
>I also noticed that you avoided answering my question, so I'll ask it
>again:
>
>So you're keeping your throttle at exactly the same position, manually,
>and if you go up or down a hill and your speed changes dramatically, so
>be it?

no, i'm not. If you read what I said, I vary the cars speed, work with
the grade (and with the road thats comming up - something NO cruise
control can do) anticipate, etc.

Cruise control programming is very simple
10 IF speed<set THEN throttle++ ELSE throttle = 0
20 goto 10

Thats putting how i've seen cruise control operation to be, rendered
into 20-odd year old Basic. If the programming is more conplex, then
it certainly doesn't come across in the driving experiance.

>
>Is that what you're doing when you drive, to avoid the throttle
>movements that are "inefficient"?

To drive efficiently, you must drive smoothly, with no sudden speed
changes, and in harmony with the othre road users around you. A cruise
control takes no notice of any enviroment except the one its driving
over at that second, and has no way of detecting other road users. It
in no way attempts to use the engine most efficiently, so HOW can it
be driving most efficiently?

flobert wrote:
> On Wed, 07 Sep 2005 13:11:41 -0400, "Elmo P. Shagnasty"
> > wrote:
>
>
>>In article >, wrote:
>>
>>
>>>To get that economy, I use no air
>>>conditioning, no cruise control
>>
>>ahem. Your BEST mileage will be when using cruise control.
>
>
> You'd think so, but experimentally, in a lot of different cars doing
> economy runs, its not. Cruise control is just to keep the car at a
> constant speed, no to do it efficiently.


i was kinda disappointed in the mileage my 98 civic CX got going from LA
to laughlin nevada and back.

if i would have taken it easy and cruised with traffic at 70-75mph, i
might have gotten more than my usual 32mpg.

but no- i had a lead foot. some of it wasnt my fault.. some grades are
so steep i had to drop it into fourth and floor it just to keep at
80mph. 5th gear was useless, the car couldnt keep up. speedo kept
dropping, even with it floored.

and of course, i had the A/C blasting in that 114 degree desert heat,
too. the mojave desert gets damned hot during the day.

so to reiterate: thats uphill, several thousand foot climbs (2000-5000
feet at a time), A/C blasting, pedal to the metal in 4th gear, doing
80mph uphill. and the temp gauge stayed below halfway! thank gawd for
mobil1 5w30.

downside? 25mpg.

In article >, flobert > wrote:

>To drive efficiently, you must drive smoothly, with no sudden speed
>changes, and in harmony with the othre road users around you. A cruise
>control takes no notice of any enviroment except the one its driving
>over at that second, and has no way of detecting other road users. It
>in no way attempts to use the engine most efficiently, so HOW can it
>be driving most efficiently?

I can think of at least one possible way *if* the car is an
automatic. It is possible (though I do not know for a fact) that
the OEM could factor in the CC in the torque converter (TC) lockup
routine. Generally the TC locks up at a certain min rpm and for a
range of throttle positions. It might be programmed to note that if
CC is engaged, throttle-based drivability concerns will not be as
big a deal at lower rpm settings. Thus it might lock it up at
non-normal speeds resulting in a more efficient transmission.

Anyway, it has been my experience that CC probably beats my mileage.
But one factor may be that if I have CC engaged, I'm driving slower
than I would otherwise.

As to the modulating throttle, I think it is a fallacy that this
markedy decreases MPG, unless done so *aggressively*. At
least in a manual where the TC doesn't come into play. Contrary to
what you might infer from your high school driving instruction, an
engine is actually more efficient at higher (but not max) throttle
setting. Accelerating doesn't consume more fuel, braking does!
(well, accel does, but it just stores it in the kinetic energy of
the car where it is available for later use). And yeah, faster
driving means higher rpm and air drag. Both of these result in
increased frictional losses.

On Fri, 9 Sep 2005 16:55:01 -0400, High Tech Misfit >
wrote:

>Dick wrote:
>
>> Cruise control will be an obvious help for those who cannot keep from
>> moving their foot up and down on the throttle on level ground without
>> a headwind. However, people who can keep their speed on level ground
>> within a couple of miles per hour can save gas when going up hill and
>> into headwinds. The cruise control will attempt to maintain speed
>> come hell or high water, even to the point of shifting down. This is
>> when a person with the ability to "feel" the car can get better
>> mileage by backing off slightly to avoid the balls to the wall effort
>> by the cruise. Under normal circumstances on the highway I will use
>> the cruise. When I get into the mountains I turn it off.
>
>All good points.
>
>I think another factor is the use of the "resume" and "accel" functions.
>The first few times I used the cruise on my '93 Accord, hitting "resume" at
>a speed significantly lower than the set speed resulted in the equivalent of
>a somewhat heavy foot (well, heavier than mine, and I'm not exactly an easy
>going driver). "Accel" produced a similar result. For that reason, when I
>accelerate to get back to my set speed, I press the gas pedal myself to not
>rush it, and then when I am at or very close to my previously set speed,
>then I "resume". To "accel", again I press the gas pedal myself to not rush
>it, and when I reach my intended speed, I "cancel" and then "set" it to the
>new speed. I found that this practice increased my gas mileage by a few
>miles per gallon.
>
>Of course, this cruise control behaviour may vary among different car
>manufacturers.

After driving my heavily loaded '98 Ody through rolling hills on the
Interstate, I have found that a steep hill will cause the transmission
to downshift where I would just let the speed drop off a little.

I agree that use of resume/accell causes too aggressive acceleration.
It also lacks any intelligence. It will downshift even if it is only
3 mph below the target speed. Are newer models more intelligent?

A better solution: manual transmission.

On Tue, 06 Sep 2005 06:30:25 -0500, Rob wrote:
>I was concerned that gas stations would be closed based on news
>reports earlier so I wanted to be sure to do this trip on one tank of
>gas tho it turned out gas stations were open. I calculated I got 37.5
>mile/gal and I was totally surprised. I'm sure it's not a mistake
>too. Normally city driving I get around 24 mile/gal.

I believe.

I get 32-33 per tank doing mostly freeway commuting, some at 80mph,
some at 5mph, most somewhere in between, a little city driving at each
end. That's by myself, no air, mostly, and with the automatic. Flat
route, btw.

Been driving a mixed route with a 500 foot rise through the Sepulveda
pass recently, ought to measure my mileage again, doesn't seem all
that different.

J.

On Sat, 10 Sep 2005 12:41:13 GMT, (Dave) wrote:

>In article >, flobert > wrote:
>
>>To drive efficiently, you must drive smoothly, with no sudden speed
>>changes, and in harmony with the othre road users around you. A cruise
>>control takes no notice of any enviroment except the one its driving
>>over at that second, and has no way of detecting other road users. It
>>in no way attempts to use the engine most efficiently, so HOW can it
>>be driving most efficiently?
>
>I can think of at least one possible way *if* the car is an
>automatic. It is possible (though I do not know for a fact) that
>the OEM could factor in the CC in the torque converter (TC) lockup
>routine. Generally the TC locks up at a certain min rpm and for a
>range of throttle positions. It might be programmed to note that if
>CC is engaged, throttle-based drivability concerns will not be as
>big a deal at lower rpm settings. Thus it might lock it up at
>non-normal speeds resulting in a more efficient transmission.
>
>Anyway, it has been my experience that CC probably beats my mileage.
>But one factor may be that if I have CC engaged, I'm driving slower
>than I would otherwise.
>
>As to the modulating throttle, I think it is a fallacy that this
>markedy decreases MPG, unless done so *aggressively*. At
>least in a manual where the TC doesn't come into play. Contrary to
>what you might infer from your high school driving instruction, an
>engine is actually more efficient at higher (but not max) throttle
>setting. Accelerating doesn't consume more fuel, braking does!
>(well, accel does, but it just stores it in the kinetic energy of
>the car where it is available for later use). And yeah, faster
>driving means higher rpm and air drag. Both of these result in
>increased frictional losses.

Dunno if this last paragraph was directed at me or not. Engine is most
efficient at arond its peak torque area. (at least for non vtec
engines) I'm not sure about them, having not had much experiance of
them. I personally didn't learn about anything at high school (since
i'm not american, and thus never went to one) but what i learnt about
cars, i learnt in my teens, working on my fathers rally car, and doing
the old economy rally's. Those were fun, slingshotting the car around
the peak torque area, and using a saab freewheeling unit in between.

In article >, flobert > wrote:

>Dunno if this last paragraph was directed at me or not. Engine is most
>efficient at arond its peak torque area. (at least for non vtec
>engines)

I think that is close, but at peak torque, most if not all engines
go into fuel enrichment. So, they won't be terribly efficient
there. Highest efficiency is typically about 20% or so below the
peak torque for that rpm judging from the fair number of brake
specific fuel consumption maps I've seen. That's still a very high
throttle setting which you won't see in typical cruise.

On Sat, 10 Sep 2005 21:49:11 GMT, (Dave) wrote:

>In article >, flobert > wrote:
>
>>Dunno if this last paragraph was directed at me or not. Engine is most
>>efficient at arond its peak torque area. (at least for non vtec
>>engines)
>
>I think that is close, but at peak torque, most if not all engines
>go into fuel enrichment. So, they won't be terribly efficient
>there. Highest efficiency is typically about 20% or so below the
>peak torque for that rpm judging from the fair number of brake
>specific fuel consumption maps I've seen. That's still a very high
>throttle setting which you won't see in typical cruise.

Possibly a difference between US and EU tunes

> <Rob> wrote in message ...
> > Just thought this gas mileage story might be worth noting for some
> > Honda Accord buyers.
> >
> > I just took my first long ride with this car this past weekend from
> > Houston, Texas to Austin, Texas and back. I used cruise control 99
> > percent of the time and had 2 adults, 2 teenagers and baggage and air
> > conditioning 100 percent of the time. I locked in the cruise control
> > at about 66 or 67 mph (speed limit said 70) and just stayed mostly in
> > the right lane to allow cars/trucks to pass me.

Why not keep up with the pace of traffic rather then being an hazard?

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