Go Back   EcoModder Forum > EcoModding > General Efficiency Discussion
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 09-10-2009, 11:41 PM   #21 (permalink)
Banned
 
Join Date: Feb 2008
Location: california
Posts: 1,329
Thanks: 24
Thanked 160 Times in 106 Posts
The comments on the autoblog article are surprisingly intelligent. Seem like most people have a concept of gallons per mile much more so than the editor.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 09-10-2009, 11:55 PM   #22 (permalink)
Engineering first
 
bwilson4web's Avatar
 
Join Date: Mar 2009
Location: Huntsville, AL
Posts: 778

14 i3-REx - '14 BMW i3-REx
Last 3: 45.67 mpg (US)

17 Prime Plus - '17 Toyota Prius Prime Plus
90 day: 58.25 mpg (US)
Thanks: 73
Thanked 189 Times in 121 Posts
Thanks to friends, I've finally gotten some Jetta (maybe Golf) TDI, mph vs MPG data and updated this graph:

I'll attach my spreadsheet so folks will have the data but here is how I see it.

MPG at 75 mph is the key data point. Cars that get better than 40 MPG at 75 mph will do well in the EPA, Euro and automotive press. But if their highway mileage is under 40 MPG, they will be reported as 'dogs.' Notice that my NHW11 fits in that category but the reason for my lifetime 52+ MPG is extensive used of 65 mph as my highway speed limit. But the EPA thinks it is a 41 MPG highway car. Knowing where the 'knee in the curve is,' allows an informed driver to trade off: good, fast and cheap.

Bob Wilson
Attached Files
File Type: xls CR_mph_MPG.xls (19.0 KB, 31 views)
__________________
2019 Std. Range Plus Model 3 - 134 MPG3 || 2014 BMW i3-REx - 117 MPGe, 39 MPG
JuiceBox 40 Pro (240 VAC, 40 A), KHONS portable (120-240 VAC, 12-32 A)
Retired engineer, Huntsville, AL (five times AutoPilot saved.)

Last edited by bwilson4web; 09-11-2009 at 12:39 PM..
  Reply With Quote
Old 09-11-2009, 06:59 PM   #23 (permalink)
Master EcoModder
 
Join Date: Jul 2008
Location: Silly-Con Valley
Posts: 1,417
Thanks: 173
Thanked 226 Times in 174 Posts
Quote:
Originally Posted by bwilson4web View Post
You'll notice that:
70 mph -> 25 hp
75 mph -> 30 hp
That is still a low throttle setting to my way of thinking. I really don't think I understand what you are saying...

-soD
  Reply With Quote
Old 09-11-2009, 11:08 PM   #24 (permalink)
Engineering first
 
bwilson4web's Avatar
 
Join Date: Mar 2009
Location: Huntsville, AL
Posts: 778

14 i3-REx - '14 BMW i3-REx
Last 3: 45.67 mpg (US)

17 Prime Plus - '17 Toyota Prius Prime Plus
90 day: 58.25 mpg (US)
Thanks: 73
Thanked 189 Times in 121 Posts
Quote:
Originally Posted by some_other_dave View Post
That is still a low throttle setting to my way of thinking. I really don't think I understand what you are saying...
What happens is the 25-30 hp point is on a steep part of the power required curve. Any slight rise or additional drag requires the engine to run up that curve into higher consumption and even more inefficient power settings:


The areas of peak engine efficiency are marked by the small, red dots. You'll notice the 25-30 hp curve fall right under the last of them. Any higher power demands push the engine into inefficient, lower BSFC regions.

So it is a combination of two effects:
  • steep power slope - so any local variance in power demand will rapidly go into much higher power regions
  • upper limit of high efficiency - anything over 30 hp is going to have lower BSFC than the 25-30 hp region.
I've thought about making a cruise control device that limits the peak HP setting, just using the ICE rpm of say 2,600 rpm AND a maximum speed. The car would slow down going up a hill but it would stay in a fuel efficient mode. But it in an actual design, I would allow excursions up to 3,400 rpm to handle hills. If any more is needed, the accelerator would be used.

Bob Wilson
__________________
2019 Std. Range Plus Model 3 - 134 MPG3 || 2014 BMW i3-REx - 117 MPGe, 39 MPG
JuiceBox 40 Pro (240 VAC, 40 A), KHONS portable (120-240 VAC, 12-32 A)
Retired engineer, Huntsville, AL (five times AutoPilot saved.)
  Reply With Quote
Old 09-12-2009, 11:35 AM   #25 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 21,391

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.8 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 73.57 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)
Thanks: 3,166
Thanked 6,020 Times in 3,121 Posts
... and the misinformation continues to spread

This time at cars.com:

At Highway Speeds, Mileage Drops More for Fuel-Efficient Models - link to article
As with the AutoBlog piece, a few commenters immediately point out the flaw in the analysis. And then they're countered by people who insist on things like:

Quote:
I've found just the opposite on my 95 Neon. During my latest trip ... I went between 75-80 the entire way and got on average 42mpg. Whereas going slower I generally only get between 35-37mpg.
...and...

Quote:
I also get better mpg the faster I drive. I used to have a 91 Civic 5-spd and I always got the best mileage out of it if I drove above 80 mph. I'm beginning to notice the same with my 04 Mazda3.
Sheesh.
__________________
Latest mods test: 15 mods = 15% MPG improvement: A-B test, 2007 Honda Civic 1.8L, 5-speed
Ecodriving test:
Manual vs. automatic transmission MPG showdown: Nissan Micra 1.6L



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
Old 09-12-2009, 01:22 PM   #26 (permalink)
EcoModding Lurker
 
Join Date: Aug 2009
Location: Baltimore
Posts: 38

03 OZ - '03 Mitsubishi Lancer OZ Rally
90 day: 34.67 mpg (US)
Thanks: 7
Thanked 4 Times in 3 Posts
Quote:
Originally Posted by MetroMPG View Post
This time at cars.com:

At Highway Speeds, Mileage Drops More for Fuel-Efficient Models - link to article
As with the AutoBlog piece, a few commenters immediately point out the flaw in the analysis. And then they're countered by people who insist on things like:

...and...

Sheesh.
It is quite funny, but I had a similar experience. Before I got my Lancer I used to drive a Neon and averaged about 200 miles per tank (back then I didn't use to pay too much attention to milage so this is as exact as I can get). One summer however I undertook a road trip to Canada and was in a bit of a rush getting home where I did 80 - 85 mph the whole way home with very few brakes on the 800 mile trip. Surprisingly, I got almost 280 miles out of my last tank on that trip. Considering how fast I was going this surprised me back then, compared to my usual highway speed of 65.

In retrospect I realize that there were a few favorable factors that helped with the big mileage jump: first it was exclusively highway driving, my regular tanks always included about 30-40% city driving and as I now know, without proper driving technique city really kills gas mileage. Second, for about 3/4 of the tank I was following a Jeep Wrangler that seemed to be in as much a hurry as me. I was following behind at a reasonable difference but at that speed, even that probably had an impact on my mileage. Lastly, going from Pittsburgh to Baltimore has a net negative elevation change of more than 1000 feet so that probably wasn't detrimental to my mileage either.

I guess what I'm trying to say is that a lot of people who are not very informed on the subject, may pull generalizations from similar personal experiences, not realizing that they're missing vital parts of the puzzle.
__________________

Last edited by Luxbg; 09-12-2009 at 01:32 PM..
  Reply With Quote
The Following User Says Thank You to Luxbg For This Useful Post:
mikeyjd (06-11-2013)
Old 09-12-2009, 04:58 PM   #27 (permalink)
Master EcoModder
 
Join Date: Nov 2008
Location: Madison AL
Posts: 1,123

The Geo - '93 Geo Metro
Team Metro
90 day: 45.16 mpg (US)
Thanks: 30
Thanked 40 Times in 37 Posts
The comments on Consumer Report are getting worse and worse.
  Reply With Quote
Old 09-12-2009, 07:45 PM   #28 (permalink)
Engineering first
 
bwilson4web's Avatar
 
Join Date: Mar 2009
Location: Huntsville, AL
Posts: 778

14 i3-REx - '14 BMW i3-REx
Last 3: 45.67 mpg (US)

17 Prime Plus - '17 Toyota Prius Prime Plus
90 day: 58.25 mpg (US)
Thanks: 73
Thanked 189 Times in 121 Posts
I posted a pointer to this chart at the Consumer Reports comments:


Personally, if this has 'struck a chord' with various vehicle advocates, it will be a good thing. Maybe they'll get busy and start measuring actual vehicle performance.

Bob Wilson
__________________
2019 Std. Range Plus Model 3 - 134 MPG3 || 2014 BMW i3-REx - 117 MPGe, 39 MPG
JuiceBox 40 Pro (240 VAC, 40 A), KHONS portable (120-240 VAC, 12-32 A)
Retired engineer, Huntsville, AL (five times AutoPilot saved.)
  Reply With Quote
Old 09-13-2009, 07:49 PM   #29 (permalink)
...beats walking...
 
Join Date: Jul 2009
Location: .
Posts: 6,191
Thanks: 179
Thanked 1,521 Times in 1,122 Posts
paraphrasing a VERY old quotation: "...you can lead an idjiot to data, but you can't make him/her believe it."

...perceptions are an 'individuals' information filters...they only let 'in' what that individual wants to hear or see.
  Reply With Quote
Old 09-25-2009, 01:11 AM   #30 (permalink)
Chevy and CB Radio Lover
 
Jammer's Avatar
 
Join Date: Sep 2009
Location: East Kentucky
Posts: 302
Thanks: 13
Thanked 3 Times in 3 Posts
Send a message via Yahoo to Jammer
Gang:

We just can not trust Consumer reports as a sole source to base our car purchases on. I have read their mag off and on through the years and I don't think I even once agreed with them on products that I knew something about. It's a cool idea to have a service that does not supposed to except advertising, but that just opens the doors to kick-backs, just like we have in politics. I am NOT accusing Consumer reports of such practices, but I often scratch my head in wonder as to why and how they conclude their winners from their losers. Sometimes things are good because they are heavy and sturdy, then something is good because it is lightweight and flexible.... I just want to scream when I read their review of products that I already know the details of. I can not think of a single time I agreed with them.

  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Reviving a 2000 Honda Insight "beater" Red Hybrids 215 08-10-2017 07:35 PM
Tested: speed vs MPG - 2006 Toyota Corolla automatic MetroMPG General Efficiency Discussion 28 05-11-2016 10:00 PM
Honda Insight owner slows down: MPG up 14% MetroMPG Hybrids 4 11-28-2009 05:44 AM
Honda Insight Concept to Debut at Paris Int. Auto Show SVOboy EcoModder Blog Discussion 32 04-17-2009 10:45 AM
Honda Insight Debuts at Detroit SVOboy EcoModder Blog Discussion 0 01-12-2009 08:50 AM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com