Home » Public Forums » GMCnet » MPG vs driveablilty
| MPG vs driveablilty [message #149636] |
Mon, 14 November 2011 10:50  |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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We are all trying to get better MPG both in the GMC and our personal vehicles.
I recently bought a new 2011 GMC pickup with a 5.3L engine. It has some technology to run on 4 cylinders, variable valve timing (I'm told) and a 6 speed transmission. Its suppose to get 9.5 l/100km on the hyway and 14.4 l/100km in the city. It carries my tool kit (15lbs) has a tonnel cover.
My old truck got passed down as a new shop truck. Its a 2005 Chev with a 5.7l engine. It has a cab-high cap on the back and carries about 1000 lbs of equipment and tools.
We needed to go to a site about 4hrs round trip away. For fun we both fueled up and reset the Ave Mpg display.
The result new truck 12.2 l/100kms Avg and the old truck was 12.4. we refueled when we returned and both took about the same fuel.
The new truck does about 1400rpm at 100kms/hr. On flat level hyways it goes to 4 cylinder mode and the instantaneous MPG drops to about 9.5ish l/100kms. However it doesn't take much to drop back to 8 cylinder mode. I think the engine computer runs under windoze as it takes it a while to decide to shift back, like a long hesitation. If cruise is on, then you have lost some speed and suddenly its shift down & 3600 rpm to gain back 6-7kms. Not fun. Watching the instantaneous MPG, what you gain in the 4 cylinder mode is lost shifting out and gaining back speed.
With the old truck the engine is right there, step on it, no hesitation it just goes. You can tell its loaded with some weight though. It never gets MPG below likely 11 l/100kms, it just lumbers along at a constant speed not needing to shift down, unless its a steep grade.
When I get my new truck loaded up the same, I think I'll be using Tow/Haul mode alot.
So GMC has thrown a few million $ at developing all this technology and added it to the price of the vehicle. In real life when this truck gets loaded up, I think I'll lose MPG compared to the old.
Sorry for the metric.
Just my experience.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: [GMCnet] MPG vs driveablilty [message #149639 is a reply to message #149636] |
Mon, 14 November 2011 12:53  |
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ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
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For us MPG folks who use US Gallons I believe the translation is as follows:
We are all trying to get better MPG both in the GMC and our personal vehicles.
I recently bought a new 2011 GMC pickup with a 5.3L (323 Cu In) engine. It has some technology to run on 4 cylinders, variable valve timing (I'm told) and a 6 speed transmission. Its suppose to get 9.5 l/100km (24.76 MPG) on the hyway and 14.4 l/100km (16.33 MPG) in the city. It carries my tool kit (15lbs) has a tonnel cover.
My old truck got passed down as a new shop truck. Its a 2005 Chev with a 5.7l (347 Cu In - but let's call it a 350) engine. It has a cab-high cap on the back and carries about 1000 lbs of equipment and tools.
We needed to go to a site about 4hrs round trip away. For fun we both fueled up and reset the Ave Mpg display.
The result new truck 12.2 l/100kms (19.28 MPG) Avg and the old truck was 12.4 (18.97 MPG). we refueled when we returned and both took about the same fuel.
The new truck does about 1400rpm at 100kms/hr. On flat level hyways it goes to 4 cylinder mode and the instantaneous MPG drops to about 9.5ish l/100kms (24.76 MPG). However it doesn't take much to drop back to 8 cylinder mode. I think the engine computer runs under windoze as it takes it a while to decide to shift back, like a long hesitation. If cruise is on, then you have lost some speed and suddenly its shift down & 3600 rpm to gain back 6-7kms. Not fun. Watching the instantaneous MPG, what you gain in the 4 cylinder mode is lost shifting out and gaining back speed.
With the old truck the engine is right there, step on it, no hesitation it just goes. You can tell its loaded with some weight though. It never gets MPG below likely 11 l/100kms (21.38 MPG), it just lumbers along at a constant speed not needing to shift down, unless its a steep grade.
When I get my new truck loaded up the same, I think I'll be using Tow/Haul mode a lot.
So GMC has thrown a few million $ at developing all this technology and added it to the price of the vehicle. In real life when this truck gets loaded up, I think I'll lose MPG compared to the old.
Ain't the internet great!
Larry Davick
Fremont, California
The Mystery Machine
'76 (ish) Palm Beach
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Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
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| Re: MPG vs driveablilty [message #149668 is a reply to message #149636] |
Mon, 14 November 2011 21:44 |
Craig Lechowicz
Messages: 541
Registered: October 2006
Location: Waterford, MI
Karma: 0
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Bruce,
You didn't say how new, (miles or kilometers) the new truck is. But, depending on that, it may get better as you've owned it. I'm sure it has changed now, but back in the late 80's when I was doing corporate average fuel economy, studies showed fuel economy improved until somewhere between 20,000 and 30,000 miles, (32,000 - 48,000 km) and then very slowly dropped again. With tighter tolerances nowadays, best fuel economy probably comes a lot sooner, but not right away.
And, the cap has a good chance of helping fuel economy slightly. When they did electric S10 pickups also in the late 80's, they spent a ton of time studying box coverings, and ultimately found that covering the rear 1/2 of the bed with a tonneau cover produced the best mpg, so they included one with them. Results might be different with different sizes and shapes on full size trucks, though.
For highway driving, 1,000 lbs. won't make much difference in mileage, but it definitely hurts in stop and go.
To make a long story short, might be too soon to make an even up comparison.
Craig Lechowicz
'77 Kingsley, Waterford, MI
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| Re: MPG vs driveablilty [message #149677 is a reply to message #149652] |
Tue, 15 November 2011 04:45 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| RF_Burns wrote on Mon, 14 November 2011 18:11 |
I ran **SNIP**
Best mileage is when I relax and drive at 90Kms (thats 55 Ken). Why speed? I'm on holidays!
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I can run in metric. I'll be in Ontario late this week or early next week having to read those high number signs that really mean you are going slow and buying fuel by the quart (liter).
You will never see a speed limit 100 or 110 sign here.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: MPG vs driveablilty [message #149687 is a reply to message #149636] |
Tue, 15 November 2011 08:06 |
WayneB
Messages: 233
Registered: July 2008
Location: Ontario, Canada
Karma: 0
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Sorry to say this Bruce, but you should have bought a Toyota Tundra pickup.
I used to be a 100% GM guy, but after 1997 the quality of their products went into a steep decline and became no better than Chrysler junk.
Going over to Toyota wasnt an easy decision for me, but now I have I have never been more satisfied with any truck I have owned.
1976 23' GMCII By Explorer
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| Re: MPG vs driveablilty [message #149689 is a reply to message #149668] |
Tue, 15 November 2011 09:07 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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| Craig Lechowicz wrote on Mon, 14 November 2011 19:44 |
... back in the late 80's when I was doing corporate average fuel economy, studies showed fuel economy improved until somewhere between 20,000 and 30,000 miles, (32,000 - 48,000 km) and then very slowly dropped again. ...
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I have also read somewhere (a tire site) the fuel economy improves was tire tires wear down. The difference is small but measurable. This is something that large truck companies pay attention to.
I do not think it is a good enough reason to have your tires trued (shaved)... but it is a plus!
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: MPG vs driveablilty [message #149719 is a reply to message #149636] |
Tue, 15 November 2011 17:10 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Back to the title of the thread.... I always thought that drivability, emissions and MPG were not mutually exclusive, but rather usually tracked together.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] MPG vs driveablilty [message #149724 is a reply to message #149687] |
Tue, 15 November 2011 18:44 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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We buy Fords or Dodges. Every now and again try something else. The Chev and Toyota products simply don't survive in the environment we subject them to. We're pragmatists.
The haulers I see at shows are pretty much all Ford or Dodge diesels, with the occasional Chev diesel included. No Toyotas or Tight Ones to be seen. Box trucks seem to be Isuzus for the small ones, Internationals for the bigger. Again, these people tend to be pragmatists, they want cheap to operate and reliable.
--johnny
________________________________
From: Wayne Barratt <waynebarratt@msn.com>
To: gmclist@temp.gmcnet.org
Sent: Tuesday, November 15, 2011 9:06 AM
Subject: Re: [GMCnet] MPG vs driveablilty
Sorry to say this Bruce, but you should have bought a Toyota Tundra pickup.
I used to be a 100% GM guy, but after 1997 the quality of their products went into a steep decline and became no better than Chrysler junk.
Going over to Toyota wasnt an easy decision for me, but now I have I have never been more satisfied with any truck I have owned.
--
1976 23' GMCII By Explorer
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: MPG vs driveablilty [message #149847 is a reply to message #149636] |
Wed, 16 November 2011 21:54 |
kingd
Messages: 592
Registered: June 2004
Karma: 2
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Re METRIC( no booing please) way back, the U.S. was going to go metric. In Canada, the excuse was"the U.S. is our largest trading partner and if they are metric, Canada has to be metric."
In the U.S. on some Interstates, the poles were installed for the metric distance signs.
In the U.S. there was a petition with less than 100,000 names against metric that went I guess to Congress and the metrification never happened. In Canada despite a petition with about as many names, Canada "blindly" pushed ahead with metric.
With the U.S. being still non-metric I guess what we have in North America is a "salad". To Ken Burton, remember the 100 on the Canadian speed limit signs is kilometers per hour. This isn't Germany( that is metric I think but one can drive 100 MPH !!!)
DAVE KING
Toronto !!!
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
[Updated on: Thu, 17 November 2011 15:54] Report message to a moderator |
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| Re: [GMCnet] MPG vs driveablilty [message #149927 is a reply to message #149847] |
Thu, 17 November 2011 17:03 |
Kingsley Coach
Messages: 2691
Registered: March 2009
Location: Nova Scotia Canada
Karma: -34
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Ken
As I'm sure you know, multiply by 6 and you have an approx speed...there is
an automatic 'grace' period of 7k per hr. So 100 k/hr is really 107 which
is really 66mph and the 110 with fudge factor is 117 or 72.657 or 75mph
approx.
Confused??
Don't worry about it, the price of gas will have you at a crawl
anyway...<VBG>
Mike in NS
On Wed, Nov 16, 2011 at 11:54 PM, Dave King <kingd@sympatico.ca> wrote:
>
>
> Re METRIC( no booing please) way back, the U.S. was going to go metric. In
> Canada, the excuse was"the U.S. is our largest trading partner and if they
> are metric, Canada has to be metric."
> In the U.S. on some Interstates, the poles were installed for the metric
> distance signs.
> In the U.S. there was a petition with less than 100,000 names against
> metric that went I guess to Congress and the metrification never happened.
> In Canada despite a petition with about as many names, Canada "blindly"
> pushed ahead with metric.
> With the U.S. being still non-metric I guess what we have in North America
> is a "salad". To Ken Burton, remember the 100 on the Canadian speed limit
> signs is kilomters per hour. This isn't Germany( that is metric I think but
> one can drive 100 MPH !!!)
>
> DAVE KING
> Toronto !!!
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS
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