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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 09-09-2009, 02:24 PM   #1 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,534

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

MPGiata - '90 Mazda Miata
90 day: 54.46 mpg (US)

Appliance car Mirage - '14 Mitsubishi Mirage ES (base)
90 day: 57.73 mpg (US)
Thanks: 4,082
Thanked 6,979 Times in 3,614 Posts
Consumer Reports tests speed vs MPG & comes to false conclusion about Honda Insight 2

When I saw that Consumer Reports had recently done a comparison of the fuel consumption of various cars over a range of speeds (55, 65 & 75 mph), my first thought was: "good, more data to add to the pile."

Here's their data:



All well and good, right? You could make some strong, logical conclusions from those figures. Right?

Apparently not if you're Consumer Reports!

Here's what they concluded and decided to highlight about the 2nd gen Honda Insight:

Quote:
The Honda Insight hybrid showed the largest drop in fuel economy — over 15 mpg going from 55 to 75 mph. [...] Vehicles with lower fuel efficiency had the smallest drop.
That statement is misleading at best, and outright wrong if you examine the numbers in a meaningful way.

If we accept that fuel economy is the relationship between fuel used and distance travelled, then the Insight's absolute increase in fuel consumption caused by increasing speed actually lies closer to the middle of the pack of the vehicles tested.

You can see this if you use litres/100 km (or you could use gallons/100 miles):



So the Insight may have had the biggest numerical MPG drop of the vehicles tested, but that's not the same as the largest change in fuel economy of the fleet.

It's pretty clear that in terms of energy consumption, emissions, and money, the absolute costs of increasing speed (ie. most meaninful in the real world) are largest in the vehicles we would expect (the bigger ones with the largest engines).

This is a glaring example of how MPG can be a misleading/confusing metric for consideration of fuel economy: I can only assume the writer saw the Insight's apparently "massive" 15 mpg drop and it drew her focus.

__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



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
The Following 12 Users Say Thank You to MetroMPG For This Useful Post:
AJI (01-31-2010), Christ (09-11-2009), Daox (09-09-2009), dremd (09-17-2009), Formula413 (09-11-2009), Funny (09-10-2009), jkp1187 (09-09-2009), mikeyjd (06-03-2014), orange4boy (01-29-2010), Silveredwings (01-29-2010), SVOboy (09-09-2009), vtec-e (09-25-2009)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 09-09-2009, 02:34 PM   #2 (permalink)
EcoModding Apprentice
 
Join Date: Dec 2007
Location: Ventura, Ca
Posts: 112

Whoop's Wheels - '89 Honda Civic Wagovan
90 day: 39.09 mpg (US)
Thanks: 1
Thanked 9 Times in 7 Posts
It is very interesting how information can sometimes be presented, which is factual, but not necessarily correct in the respect of the right question, rather than a question. The data they presented is technically correct, but the way in which it is presented does make it appear that the insight is a "worse" performing vehicle and the way it is presented implies that it will give the user the worst value in mpg, which is completely not true.

Very interesting example of totally correct, misinformation.
  Reply With Quote
The Following 2 Users Say Thank You to Whoops For This Useful Post:
bryan11 (01-29-2010), vtec-e (09-25-2009)
Old 09-09-2009, 02:43 PM   #3 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,534

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

MPGiata - '90 Mazda Miata
90 day: 54.46 mpg (US)

Appliance car Mirage - '14 Mitsubishi Mirage ES (base)
90 day: 57.73 mpg (US)
Thanks: 4,082
Thanked 6,979 Times in 3,614 Posts
I would have said her statement was correct if she'd said the Insight experienced the "largest drop in MPG" rather than "fuel economy".
__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



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 09-09-2009, 03:17 PM   #4 (permalink)
...beats walking...
 
Join Date: Jul 2009
Location: .
Posts: 6,190
Thanks: 179
Thanked 1,525 Times in 1,126 Posts
...they're all "...LIES, damn LIES, and STATISTICS..." , said Humorist Will Rogers.

...you'd figure they'd look at the "rates-of-change" or something, NOT the absolute numbers.
  Reply With Quote
Old 09-09-2009, 04:06 PM   #5 (permalink)
Master EcoModder
 
tasdrouille's Avatar
 
Join Date: Jan 2008
Location: Mirabel, QC
Posts: 1,672

The Guzzler - '08 Hyundai Elantra GL
90 day: 33.12 mpg (US)

Got Soul? - '11 Kia Soul 2U
Thanks: 35
Thanked 86 Times in 57 Posts
Well, if you ask me the conclusion is not necessarily wrong. The Insight did have the biggest relative percentage drop in fuel economy. This just means that as speed increases its fuel economy goes down at a faster rate than other cars tested.
__________________



www.HyperKilometreur.com - Quand chaque goutte compte...
  Reply With Quote
The Following User Says Thank You to tasdrouille For This Useful Post:
bryan11 (01-29-2010)
Old 09-09-2009, 04:26 PM   #6 (permalink)
eco....something or other
 
Join Date: Jul 2009
Location: Colfax, WI
Posts: 724

wood hauler - '91 Ford F-250
Team Pontiac
90 day: 26.69 mpg (US)

Rav - '06 Toyota Rav4 Base
90 day: 26.52 mpg (US)
Thanks: 39
Thanked 67 Times in 50 Posts
even at 75 mph the insight is still blowing the competition out of the water!!!

I don't like consumer reports anyway because they almost always vote for the ones that are crap.....
__________________



1991 F-250:
4.9L, Mazda 5 speed, 4.10 10.25" rear
  Reply With Quote
The Following User Says Thank You to IsaacCarlson For This Useful Post:
dremd (09-17-2009)
Old 09-09-2009, 04:36 PM   #7 (permalink)
Banned
 
Join Date: Feb 2008
Location: california
Posts: 1,329
Thanks: 24
Thanked 161 Times in 107 Posts
Consumer reports already decided to the new Insight is crap in a previous issue. Now they are just trying to reinforce that point of view. You should email them on this.
  Reply With Quote
Old 09-09-2009, 04:40 PM   #8 (permalink)
EcoModding Apprentice
 
Join Date: Oct 2008
Location: up north
Posts: 196
Thanks: 4
Thanked 34 Times in 26 Posts
We could quibble about who had the biggest percentage drop, depending on how you compute it, blah blah blah.

But I did notice that the Insight still returned the best fuel economy of the vehicles in the test cohort, even at 75 mph.

I would also note that I'm pretty sure I could beat the Insight with my 04 VW diesel at 75 mph, and maybe the other speeds as well. Admittedly, that's using hypermiling techniques, while they are following some "normal" protocol.

Finest regards,

troy
__________________
2004 VW TDI PD on bio

want to build 150 mpg diesel streamliner.
  Reply With Quote
Old 09-09-2009, 05:10 PM   #9 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,534

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

MPGiata - '90 Mazda Miata
90 day: 54.46 mpg (US)

Appliance car Mirage - '14 Mitsubishi Mirage ES (base)
90 day: 57.73 mpg (US)
Thanks: 4,082
Thanked 6,979 Times in 3,614 Posts
Quote:
Originally Posted by tasdrouille View Post
The Insight did have the biggest relative percentage drop in fuel economy.
You're right: relative to its first value (at 55 mph), the Insight had the steepest change in fuel economy at 75 mph (regardless of whether MPG, L/100 km, or gallons/100 miles is used).

But I still feel that absolute (vs. relative) fuel economy figures are more meaningful/useful to the average person in a comparison like this. The writer has decided that the slope of the graph is more significant than the actual fuel used in the change from 55 to 75:

Quote:
...the most significant change in fuel economy comes from the most fuel-efficient vehicles we tested.
Is the slope of a graph more "significant" to the average consumer than the actual change in fuel consumption? Hmm...

---

tjts1: they have comments under this Consumer Reports piece. Since I posted this, someone has brought up the same topic. (Not me!)

Commenter says:

Quote:
This is one place where the difference of the real cost is much better understood in gallons per mile, rather than miles per gallon. The insight's cost for speeding is far less significant than the Mountaineer's loss of "only 6 MPG."
__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



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 09-09-2009, 08:26 PM   #10 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,762

Blue - '93 Ford Tempo
Last 3: 27.29 mpg (US)

F150 - '94 Ford F150 XLT 4x4
90 day: 18.5 mpg (US)

Sport Coupe - '92 Ford Tempo GL
Last 3: 69.62 mpg (US)

ShWing! - '82 honda gold wing Interstate
90 day: 33.65 mpg (US)

Moon Unit - '98 Mercury Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 1,585
Thanked 3,555 Times in 2,218 Posts
You should go fix her wagon.

__________________


  Reply With Quote
Reply  Post New Thread




Similar Threads
Thread Thread Starter Forum Replies Last Post
Reviving a 2000 Honda Insight "beater" Red Hybrids 215 08-10-2017 08:35 PM
Tested: speed vs MPG - 2006 Toyota Corolla automatic MetroMPG General Efficiency Discussion 28 05-11-2016 11:00 PM
Honda Insight owner slows down: MPG up 14% MetroMPG Hybrids 4 11-28-2009 06:44 AM
Honda Insight Concept to Debut at Paris Int. Auto Show SVOboy EcoModder Blog Discussion 32 04-17-2009 11:45 AM
Honda Insight Debuts at Detroit SVOboy EcoModder Blog Discussion 0 01-12-2009 09:50 AM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com