Comparative Steady State Higher Speed Fuel Economies

  1. Welcome to GM Inside News Forum – General discussion forum for GM

    Welcome to GM Inside News Forum - a website dedicated to all things GM.

    You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, Join GM Inside News Forum today!
     
+ Reply to Thread
Results 1 to 13 of 13

Thread: Comparative Steady State Higher Speed Fuel Economies

  1. #1
    6.2 Liter LS3 V8
    Join Date
    Aug 2007
    Posts
    3,394
    Thanks
    0
    Thanked 2 Times in 2 Posts

    Comparative Steady State Higher Speed Fuel Economies

    Comparative Steady State Higher Speed Fuel Economies from 50 to 120+ mph where possible


    Source: http://bioage.typepad.com/photos/unc.../autobild1.png

    Thought some of you might be interested.

    The graph reflects selected steady state fuel economies in mpg increments for the Prius, Mercedes C 180K plus gasoline-diesel pairs of the BMW 535 Touring, Opel Zafira, and the VW Golf.

    Take special notice of the spreads between the gasoline and diesel versions of the pairs. You may also find the variations in slopes of interest.

    Sorry about the graph size, I did not know how to make it larger.
    Last edited by ne_one; 01-25-2013 at 08:06 PM.

  2. Remove Advertisements
    GM Inside News
    Advertisements
     

  3. #2
    R2-D2 Astromech Droid Smaart Aas Saabr's Avatar
    Join Date
    Oct 2003
    Location
    Montréal, Québec
    Posts
    17,847
    Thanks
    57
    Thanked 123 Times in 91 Posts

    Re: Comparative Steady State Higher Speed Fuel Economies

    Thanks, this is very interesting!

    What stands out to me:

    1. BMW 535d -> do want!

    2. Slopes seem same between diesel and gasoline. This makes sense, the "energy consumption" of the car is equal, but the diesel makes more energy per gallon

    3. Small, weak cars seem to burn much more at speed than powerful luxury cars.

    4. 155 mph doesn't burn that much fuel...

  4. #3
    Firebird Concept (the turbine one)
    Join Date
    Aug 2008
    Posts
    12,301
    Thanks
    19
    Thanked 382 Times in 235 Posts

    Re: Comparative Steady State Higher Speed Fuel Economies

    It's interesting but somewhat expected. Cars burn more fuel the faster they go. They also get worse mileage going uphill and better fe going downhill.

  5. #4
    6.0 Liter L76 V8
    Join Date
    Jul 2005
    Posts
    2,137
    Thanks
    15
    Thanked 165 Times in 80 Posts

    Re: Comparative Steady State Higher Speed Fuel Economies

    Quote Originally Posted by Smaart Aas Saabr View Post
    2. Slopes seem same between diesel and gasoline. This makes sense, the "energy consumption" of the car is equal, but the diesel makes more energy per gallon
    You have to keep in mind that mpg is not linear. What I mean is, even though the lines may be parallel, there's a significant difference in how sharply the fuel consumption goes up.

    If one car drops from 16 mpg to 12 mpg, and another one drops from 12 mpg to 8 mpg, the curves are perfectly parallel, but the first one is consuming an extra 2.08 gallons per 100 miles, the second one is consuming an extra 4.17 gallons. It's more obvious if you loot at it in terms of fuel consumption/distance.

    Was-kostet-Vollgas-729x486-e35b83cfecf5d962.jpg

    Gas engines really start getting inefficient near wide open throttle because that's where they start running in open loop mode and injecting extra fuel for cooling. That's why the diesel doesn't have the same uptick near top speed.

  6. #5
    2.8 Liter Turbocharged V6 funkypunnk's Avatar
    Join Date
    Apr 2005
    Location
    Chicago, IL
    Posts
    946
    Thanks
    3
    Thanked 9 Times in 4 Posts

    Re: Comparative Steady State Higher Speed Fuel Economies

    What I see is that between 60 and 80 cars lose about 25% of their fuel economy regardless of engine type or size, and that by about 170mph all cars get around 5mpg, so we should all go 170 to make things fair for everyone in our socialistic world!!!!!!
    A veteran - whether active duty, retired, national guard, or reserve - is someone who, at one point in his or her life, wrote a blank check made payable to The 'United States of America', for an amount of 'up to and including my life.'




    2008 Suburban Z71
    2008 Pontiac G8
    1970 Pontiac LeMans Sport
    1966 Pontiac Catalina Ventura Convertible
    1960 Buick LeSabre Convertible

  7. #6
    6.0 Liter L76 V8 70AARCUDA's Avatar
    Join Date
    May 2011
    Posts
    2,342
    Thanks
    12
    Thanked 82 Times in 60 Posts

    Re: Comparative Steady State Higher Speed Fuel Economies

    ...DRAG increases as the square of velocity while POWER requirement increases as the cube of velocity!
    2011 Chevrolet Cruze LTZ 1.4LT 6A
    2009 Pontiac Vibe 1.8L/SFI 4A
    2004 Pontiac Vibe 1.8L/MFI 4A

    1971 Dodge Charger 318 3A
    1970½ Plymouth AAR 'Cuda 340/6BBL 4M
    1968 Dodge Charger 383 3A
    1967 Plymouth Barracuda Formula S 383 4M
    1965 Plymouth Barracuda Formula S 273 4M

  8. #7
    R2-D2 Astromech Droid Premium Member Neanderthal's Avatar
    Join Date
    Nov 2004
    Location
    Holy Toledo, Annie!
    Posts
    24,579
    Thanks
    972
    Thanked 917 Times in 582 Posts
    My Ride
    15Soul+ Yellow; 01 PT LTD

    Re: Comparative Steady State Higher Speed Fuel Economies

    I'll have to go find my old 2004 Impala and run some steady-state numbers on it. As I've oft repeated, I got my several best tanks running at 80-90 in the summer in east Tennessee, at over 33 MPG.
    No tailwind, no extraterrestrial vortex that I could determine.

    15Soul 13Charger 13Soul 11V6200 07GPGXP 07Spectra 95LHS 04Imp 03Accord 02Regal 02cordV6 01cord 99GolfTDi 98Concorde 97Concorde 97HXCiv 96Concorde 95trep 94Protege 92SHO 93Protege 92P50Taurus

    Those who dare to fail miserably can achieve greatly. --John F. Kennedy



  9. #8
    R2-D2 Astromech Droid Smaart Aas Saabr's Avatar
    Join Date
    Oct 2003
    Location
    Montréal, Québec
    Posts
    17,847
    Thanks
    57
    Thanked 123 Times in 91 Posts

    Re: Comparative Steady State Higher Speed Fuel Economies

    Quote Originally Posted by funkypunnk View Post
    What I see is that between 60 and 80 cars lose about 25% of their fuel economy regardless of engine type or size, and that by about 170mph all cars get around 5mpg, so we should all go 170 to make things fair for everyone in our socialistic world!!!!!!
    If we could drive 170 mph, even I might be interested in socialism

  10. #9
    6.2 Liter LS3 V8
    Join Date
    Aug 2007
    Posts
    3,394
    Thanks
    0
    Thanked 2 Times in 2 Posts

    Re: Comparative Steady State Higher Speed Fuel Economies

    I discovered that the original graph was generated in the 2005/6 time frame.

    Fuel Consumption at Higher Speeds
    22 May 2006

    So, that is OLD technology as far as I am concerned ... even though the relationships may be visible in current powertrain technology.

    There is more recent work (2012) that seems to demonstrate that increasing highway speed from 50 to 80 mph usually results in over a 35% loss in fuel economy average based on constant speed testing of 74 vehicles ... if I remember the data correctly.

    Here is the most recent information

    ORNL researchers quantify the effect of increasing highway speed on fuel economy

    18 January 2013

    John F. Thomas, Brian H. West and Shean P. Huff
    Fuels, Engines and Emissions Research Center, Oak Ridge National Laboratory
    Last edited by 44 mpg by 2010; 01-31-2013 at 04:27 PM.
    It is important what WE use as our "moral compass" and ...
    the "measuring stick" chosen for judging progress/success as well.


    44 mpg by 2010 ... 2013?

  11. #10
    R2-D2 Astromech Droid Smaart Aas Saabr's Avatar
    Join Date
    Oct 2003
    Location
    Montréal, Québec
    Posts
    17,847
    Thanks
    57
    Thanked 123 Times in 91 Posts

    Re: Comparative Steady State Higher Speed Fuel Economies

    The ORNL though is ****ed, since the car doesn't move at steady-state speeds in the real world.

    It is especially important when driving on hilly roads, if you are braking to keep 50 on descent, and flooring pedal to keep 50 on ascent, you are wasting tremendous fuel compared to keeping a relatively constant throttle angle and cresting at 60 and bottoming at 90.

    And also... 35% more fuel... well... who cares, life is short and driving 100 mph instead of 50 mph is cost-effective for productivity reasons

    When I monitor my own fuel consumption in real-time or in averaged time, the huge fuel consumption occurs when driving slowly, in traffic jams and on arterial streets with unsynchronized lights. I get roughly twice as much fuel economy driving at 95 mph on the highway, than at the 15 mph average along a clogged suburban arterial in the morning.

    If anything the solution is spending some money to add lane-miles, improve inadequate interchange designs, build interchanges or reconfigure intersections for improved flow, and time traffic lights to optimize flow. Maybe even consider Michigan-style "superstreet" designs (RIRO and Michigan left) instead of traffic-light controlled all-way intersections. Most vehicle-miles are driven in urban areas with speeds limited considerably by traffic flows, and not in ideal conditions where you can drive as fast as you want. 50 mph is really very fast driving for most people most of the time, even though the sign may say 65 or 70, they are sitting there stopped.
    Last edited by Smaart Aas Saabr; 01-31-2013 at 08:09 PM.

  12. #11
    6.2 Liter LS3 V8
    Join Date
    Aug 2007
    Posts
    3,394
    Thanks
    0
    Thanked 2 Times in 2 Posts

    Re: Comparative Steady State Higher Speed Fuel Economies

    You get no argument from me on any of your major points.

    As for improving roadways and interchanges, the current "party line" is cut government expenditures ... including infrastructure for vehicular traffic whether repairs, efficiency, or safety.

    .

    I spoke to one of the participants of 2013 ORNL study. One of the hopes for their research is the ability for a future fueleconomy.gov user to do a personalized more realistic estimate of potential "real world" fuel economy experience based on that individual's driving style and environment. Certainly a noble objective.
    It is important what WE use as our "moral compass" and ...
    the "measuring stick" chosen for judging progress/success as well.


    44 mpg by 2010 ... 2013?

  13. #12
    Chevrolet VOLT F14CRAZY's Avatar
    Join Date
    May 2006
    Location
    Dimondale, MI
    Posts
    10,470
    Thanks
    71
    Thanked 180 Times in 122 Posts

    Re: Comparative Steady State Higher Speed Fuel Economies

    Quote Originally Posted by Smaart Aas Saabr View Post
    The ORNL though is ****ed, since the car doesn't move at steady-state speeds in the real world.

    It is especially important when driving on hilly roads, if you are braking to keep 50 on descent, and flooring pedal to keep 50 on ascent, you are wasting tremendous fuel compared to keeping a relatively constant throttle angle and cresting at 60 and bottoming at 90.

    And also... 35% more fuel... well... who cares, life is short and driving 100 mph instead of 50 mph is cost-effective for productivity reasons

    When I monitor my own fuel consumption in real-time or in averaged time, the huge fuel consumption occurs when driving slowly, in traffic jams and on arterial streets with unsynchronized lights. I get roughly twice as much fuel economy driving at 95 mph on the highway, than at the 15 mph average along a clogged suburban arterial in the morning.

    If anything the solution is spending some money to add lane-miles, improve inadequate interchange designs, build interchanges or reconfigure intersections for improved flow, and time traffic lights to optimize flow. Maybe even consider Michigan-style "superstreet" designs (RIRO and Michigan left) instead of traffic-light controlled all-way intersections. Most vehicle-miles are driven in urban areas with speeds limited considerably by traffic flows, and not in ideal conditions where you can drive as fast as you want. 50 mph is really very fast driving for most people most of the time, even though the sign may say 65 or 70, they are sitting there stopped.
    Those "Michigan lefts" are annoying when you want to make a left pulling out of a drive
    '07 Subaru Forester 2.5X 5MT. Bought new. 164k miles. '05 Dodge Durango Limited Hemi AWD. Mom bought new. 90k miles. '74 Buick LeSabre Luxus convertible. 455/7.5L, Quadrajet, dual exhaust. '89 Buick Reatta. 3800 SII L67/F40 six speed swap to be completed someday.

    '87 BMW K75. Pichler V1 fairing. '87 Kawasaki 650SX. '85 Bayliner Capri 1952. 3.0L OMC. Restored. '71 Chris Craft Coho 33'. Twin 327QA's. Basketcase but restoration in progress. '70? Amphicat 6x6 AATV. 13 hp Honda swap.

  14. #13
    R2-D2 Astromech Droid Smaart Aas Saabr's Avatar
    Join Date
    Oct 2003
    Location
    Montréal, Québec
    Posts
    17,847
    Thanks
    57
    Thanked 123 Times in 91 Posts

    Re: Comparative Steady State Higher Speed Fuel Economies

    Quote Originally Posted by F14CRAZY View Post
    Those "Michigan lefts" are annoying when you want to make a left pulling out of a drive
    But you'd usually have a median, or too much traffic to make a decent left anyway, at least with it, you can U-turn. Around here there is a median and U turn is prohibited at all intersections, so to go left, you are basically screwed

  15. Remove Advertisements
    GM Inside News
    Advertisements
     

Quick Reply Quick Reply

Register Now

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Powered by vBadvanced CMPS v4.1.2