Maybe it is still too early to "complain" that my V6 Accord is not doing
what it says on spec.
Average MPG is around 20 to 20.5, lower than its 21/30 rating. The roads
are semi-highway averaged around 30miles/hour speed. 25 miles of commuting
cost me around 50 minutes of driving...

Am I expecting too much? Does it look normal to you? Also I found the Navi
screen shows less miles driven compared to the counter under the
speedometer. I found around 10 miles difference from 300 miles of driving.
Navi screen tends to have less miles displayed. Which one is more accurate
to use for MPG calculation?

 

harry <harry_liuNOSPAM@lcc.com> wrote:
> Am I expecting too much? Does it look normal to you? Also I found the
> Navi screen shows less miles driven compared to the counter under the
> speedometer.

The speedometer/odometer is more accurate overall. Gaps in satellite
coverage can affect the GPS-based accumulation of mileage. On windy roads,
the GPS might even cut some corners.

With a handheld GPS, I have matched my car speedometer for over a hundred
miles, and I've also had some obvious gaps. The speed indicated by the
GPS will be more accurate than the car speedometer under good conditions,
but I don't know if your Navi system displays speed.

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

 

dold@XReXXwhatX.usenet.us.com wrote:
> On windy roads, the GPS might even cut some corners.

For a few seconds, I was scratching my head wondering how wind could
affect GPS. Does it blow the satellites around or something? Then I
realized you meant "winding roads", not "windy roads" =)

 

I have a 2004 EX V6 and a similar driving pattern, except frequent
delays and crawling along at 10 mph for several miles during rush hour.
The distance is 25 miles.

I got 21 mpg brand new during the winter (no a/c on). Now at 8,300
miles, I'm getting about 23 with the a/c working hard.

If I go another route that is less congested but the same distance,
about half is 60-65 mph and the other half is 30 to 60 but interrupted
by lots of red lights. This delivers 24.5 mpg now.

It is the stops and accel/deceleration cycles that kills the gas
mileage. If you do a steady 30 mpg, a car should be able to deliver
nearly the same mileage as one doing 60 -- it just takes longer to get
there. I have noted this in several cars that were equipped with
instantaneous mpg computers.

You didn't state how many miles you have, but probably you need to let
it break in some more. I have even seen references on the MDX group
that the engine is still breaking in at 12,000 to 15,000 miles, with
measureable improvements to mileage, and measureable junk in the oil
according to oil analyses. The 3.5 liter MDX engine is just a bored
out 3.0 liter, with same VTEC valvetrain and about the same
transmission too I think.

 

Bucky <uw_badgers@email.com> wrote:
> dold@XReXXwhatX.usenet.us.com wrote:
>> On windy roads, the GPS might even cut some corners.

> For a few seconds, I was scratching my head wondering how wind could
> affect GPS. Does it blow the satellites around or something? Then I
> realized you meant "winding roads", not "windy roads" =)

Whine-dee, not breezy ;-). Winding?
Hmmm. I think you're right.

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

 

If you do a steady 30 mpg, a car should be able to deliver
> nearly the same mileage as one doing 60 -- it just takes longer to get
> there.


This string is jinxed. Let me fix my own posting:

If you do a steady 30 MPH, a car should be able to deliver
nearly the same mileage as one doing 60.

 

Harry
In town 21-23, on the freeway cruse control 28 to 33 depending on speed 65
- 75
I've had mine for 6 months



> Maybe it is still too early to "complain" that my V6 Accord is not
> doing what it says on spec.
> Average MPG is around 20 to 20.5, lower than its 21/30 rating. The
> roads are semi-highway averaged around 30miles/hour speed. 25 miles
> of commuting cost me around 50 minutes of driving...

 

I drive the same car and around town (Los Angeles) I average 18 to
20mpg; extended highway cruising it gets close to 25mpg.

 

harry <harry_liuNOSPAM@lcc.com> wrote:
> Also I found the Navi
> screen shows less miles driven compared to the counter under the
> speedometer. I found around 10 miles difference from 300 miles of driving.
> Navi screen tends to have less miles displayed. Which one is more accurate
> to use for MPG calculation?

GPS, as I understand, can measure distance travelled in horizontal plane
fairly accurately but not so accurately in vertical plane. So I would
expect GPS distance to be quite accurate on very flat roads, provided it
maintains a good satellite lock, but if there is elevation change on the
road, accuracy of distance travelled may be questionable.

================================================== ==================
Khalid
khalid AT gonehiking DOT org

 

See signature for email address wrote:
> harry <harry_liuNOSPAM@lcc.com> wrote:
>
>>Also I found the Navi
>>screen shows less miles driven compared to the counter under the
>>speedometer. I found around 10 miles difference from 300 miles of driving.
>>Navi screen tends to have less miles displayed. Which one is more accurate
>>to use for MPG calculation?
>
>
> GPS, as I understand, can measure distance travelled in horizontal plane
> fairly accurately but not so accurately in vertical plane. So I would
> expect GPS distance to be quite accurate on very flat roads, provided it
> maintains a good satellite lock, but if there is elevation change on the
> road, accuracy of distance travelled may be questionable.

4 or more satellites give a 3D fix - it was fun when I first used my GPS
unit to watch the speed, direction & altitude change as I motored around
at 2 AM (on & off an Interstate gives some nice altitude changes).

 

Sparky Spartacus <Sparky@universalexports.org> wrote:
> See signature for email address wrote:
> > harry <harry_liuNOSPAM@lcc.com> wrote:
> >
> >>Also I found the Navi
> >>screen shows less miles driven compared to the counter under the
> >>speedometer. I found around 10 miles difference from 300 miles of driving.
> >>Navi screen tends to have less miles displayed. Which one is more accurate
> >>to use for MPG calculation?
> >
> >
> > GPS, as I understand, can measure distance travelled in horizontal plane
> > fairly accurately but not so accurately in vertical plane. So I would
> > expect GPS distance to be quite accurate on very flat roads, provided it
> > maintains a good satellite lock, but if there is elevation change on the
> > road, accuracy of distance travelled may be questionable.

> 4 or more satellites give a 3D fix - it was fun when I first used my GPS
> unit to watch the speed, direction & altitude change as I motored around
> at 2 AM (on & off an Interstate gives some nice altitude changes).

Yes, 4 or more satellites will give a 3D fix but margin of error in
vertical plane is lot more than horizontal plane. I can stop at a red
light with 8 satellites locked with WAAS and watch my altitude drift on
Garmin SP2610 while staying still.

I do not understand solid geometry well enough to explain this but there
have been a few explanations on the GPS newsgroups on why GPS has a hard
time calculating vertical distances accurately. Here are some links with
some answers:

<http://www.gpsinformation.net/main/altitude.htm>
<http://www.gpsinformation.net/articles/tripdistanceerror.htm>

================================================== ==================
Khalid

khalid AT gonehiking DOT org

 

Sparky Spartacus wrote:
> 4 or more satellites give a 3D fix - it was fun when I first used my GPS
> unit to watch the speed, direction & altitude change as I motored around
> at 2 AM (on & off an Interstate gives some nice altitude changes).


i took mine from long beach ca to laughlin, nv. it was spot-on, altitude
wise. passed the sign that said 4000ft elevation, and sure enough, the
GPS read 4010.

it was also fun checking the speedo error, and actually making my CX go
over 100mph! rock solid at that speed, too.

 

SoCalMike <Mikein562athotmail@hotmail.com> wrote:
> Sparky Spartacus wrote:
> > 4 or more satellites give a 3D fix - it was fun when I first used my GPS
> > unit to watch the speed, direction & altitude change as I motored around
> > at 2 AM (on & off an Interstate gives some nice altitude changes).


> i took mine from long beach ca to laughlin, nv. it was spot-on, altitude
> wise. passed the sign that said 4000ft elevation, and sure enough, the
> GPS read 4010.

Same observation here. Every time I go over a mountain pass here in
Colorado, altitude reading on SP2610 is fairly close to the posted
elevation, but the GPS experts say elevation calculation on GPS is not
accurate and I do see large drifts in elevation even when standing
still.

================================================== ==================
Khalid
kahlid AT gonehiking DOT org

 

See signature for email address wrote:

> SoCalMike <Mikein562athotmail@hotmail.com> wrote:
>
>>Sparky Spartacus wrote:
>>
>>>4 or more satellites give a 3D fix - it was fun when I first used my GPS
>>>unit to watch the speed, direction & altitude change as I motored around
>>>at 2 AM (on & off an Interstate gives some nice altitude changes).
>
>
>
>>i took mine from long beach ca to laughlin, nv. it was spot-on, altitude
>>wise. passed the sign that said 4000ft elevation, and sure enough, the
>>GPS read 4010.
>
>
> Same observation here. Every time I go over a mountain pass here in
> Colorado, altitude reading on SP2610 is fairly close to the posted
> elevation, but the GPS experts say elevation calculation on GPS is not
> accurate and I do see large drifts in elevation even when standing
> still.

Sounds as though moving vs stationary is a factor.