broke 30MPG in a behemoth!!

Discussion in '4x4's, SUV's and P/U Trucks' started by npauli, May 22, 2009.

  1. npauli

    npauli Well-Known Member

    All the stars aligned last night for a new record for me on a single trip (that's not all downhill). I got 30.0 mpg on an 11 mile trip through town. The hills are just right where I can make some power on the uphill stretches then coast for quite a while downhill without loosing much speed. Lot's of green lights and little traffic helped.

    I realize that for many of you, 30mpg would be reason to hang your head in shame. For a truck that's over 7k empty, over 20' long, and with all the aerodynamics of a sheet of plywood held broadside, that's pretty good.

    For comparison:

    27mpg = previous best trip
    25 mpg = best long trip (~ 100 miles of illinois flatness)
    23mpg = best tank
    19mpg = best tank with previous trucks (both half ton, 2wd, reg cab with 4.XL gas engines)
    10mpg = what my dad gets around town with his slightly smaller work truck w/ a gas motor and auto.
  2. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Congrats! That's quite the achievement! :flag:
  3. nervousmini

    nervousmini Well-Known Member


    Way to go. That gives me great inspiration for my blazer - maybe I'll get a 30mpg trip myself.
  4. laurieaw

    laurieaw Sorceress of the North

    freakin' awesome. best i have managed in my GMC is 15, so i bow to your skill.
  5. MT bucket

    MT bucket I want my MPG!

    Wow, that is great mileage. i had a hard time getting that in my little minivan! you are beating the epa of almost all CARS made now, in that big pickup!
    you should enter the next 3 month fuel economy challenge! it goes be % over the EPA, not who gets the most mpgs, so any vehicle can win. :)
  6. npauli

    npauli Well-Known Member

    Alas, there are no EPA estimates for 3/4 ton pickups and larger. There's nothing even close - the closest truck with an EPA estimate would be 1/2 ton, shorter, lighter, and with a gas engine.

    That's ok though. Sometimes what's good for mpg isn't necessarily good for other things, so I don't want to put too much pressure on mpg to the detriment of other things that matter. For example, I can get better mpg taking backroads to work, but burn less fuel per trip by taking the interstate since it's more direct.
  7. fuzzy

    fuzzy Mild hypermiler

    Not here. It took me more than 11 years to learn how to get my Subaru up to 30 mpg. It weighs less than half your truck, and has the aerodynamics of only a half sheet of plywood. You done great!
    Last edited: May 23, 2009
  8. phoebeisis

    phoebeisis Well-Known Member

    Wow,-spectacular. With the wind in my favor and 4000' altitude I've gotten 24 mpg over 250 miles in the 5200 lb Suburban 1500 2wd , but no way could it get anything like 30 mpg!!

  9. abcdpeterson

    abcdpeterson Well-Known Member

    30! WoW!
    Before Hypermile I was getting 28mpg in my 1.8L wagon.
    your doing better than many people driving small cars!
    I am impressed.
    that's got to feel Good, congratulations
  10. blownb310

    blownb310 Well-Known Member

    Did you do this completely by hypermiling it, or did you make any changes to the truck itself?
  11. Chuck

    Chuck just the messenger

    This probably equates to getting 110mpg or better in a 5-speed Honda Insight.

  12. drimportracing

    drimportracing Pizza driver: 61,000+ deliveries

    Congratulations! Great achievement. Keep on truckin' :D - Dale
  13. npauli

    npauli Well-Known Member

    No mods. Well, ok, I added an oil pan heater, but only use it in winter.
    Diesel's great to start with, The 01-early04 duramax is a particularly good engine for FE, 6 speed helps, and the axle ratio is tall. Powertrain is actually a really good combination for moving that much metal around. The truck can do 20 mpg without any intentional HM.
  14. Silverado

    Silverado Member

    What is the body style on that rig? It sounds like a 4 door, Long bed, 4wd. Is that accurate?

    What size engine?

    What is 1st gear like on that Allison? I have been thinking about that but for its purpose, I have thought it is a creeper/granny/tractor/high-torque gear or whateer you want to call it. In the owners manual I believe it recommends a 2nd gear start usually.

    I am just curious to know how your truck compares to mine. Post some pictures maybe?

    I drive a 2004 Silverado as well, but with a much smaller pricetage :D

    EDIT: Saw the stump pulling picture. That is an awesome looking truck, and I can't imagine it in a manual either. Great color too.

    I have a 2004 Chevrolet Silverado. It has The 4.3 V6 which puts out 260ft/lb's of torque which isn't bad. It's a regular cab with the short bed. Also has teh NV3500 5MT transmission. All of this is good for 25.5 mpg on the highway going 60-65mph. I just logged that over a 475mile round trip.
    Last edited: Aug 10, 2009
  15. phoebeisis

    phoebeisis Well-Known Member

    npauli- WOW!!

    A couple of questions.
    1)MT or AT?
    2) In top gear how many RPMs do you do at 60 mph?
    3)Any idea how the 6.6 Duramax does mpg wise? I've heard it doesn't do as well as the earlier 6.0 Duramax.

    I'm interested because I'm always scouting for something that would get me better mpg than my 98 Suburban-5.7 1/2 ton 2 wd.We have it to haul 'stuff" and just in case we need to evacuate 3 adults, 2 leggy dogs, 4 cats. The cats have to be in a HUGE folding crate,so the Prius+another car won't work.

    I've seen some 2007 Chevy Diesel 6.6 vans -AT- on Ebay for about $10,000.My suspicion is that they wouldn't beat the 21 mpg hy that the Suburban gets.
    What do you hear about the 6.6?

  16. Silverado

    Silverado Member

    Based on his signiture, it is the biggest truck money can buy and has the 6 speed manual transmission. Looks like he consistantly gets around 22mpg as well.
  17. npauli

    npauli Well-Known Member

    In respose to questions, here's more truck details:

    CCLB = crew cab, long bed
    ~ 21' long
    ~ 7000 lb empty
    tires oversized one notch (265-75R16 vs 245) giving about 3% overdrive. I account for this in mileage calcs, but speedo/odo aren't corrected.

    6.6L Duramax diesel (LB7)
    300 HP at 3100?
    520 ft-lb at 1800
    high pressure common rail
    mechanical wastegate
    completely stock

    ZF S6-650 6 speed manual
    1st gear only used when hauling heavy
    6th gear puts 65mpg at about 1800 rpm

    I've never heard of a 6.0 Duramax. Are you thinking of the Ford 6.0? The different year 6.6 Duramax's are, (from best FE to worst)

    LB7 (2001-early 2004)
    LBZ (2006-early 2007, improved LLY)
    LLY (mid 2004-2005, added EGR)
    LMM (mid 2007 - early 2010, LBZ + DPF)

    If I remember right, the vans get the same Duramax as the trucks, but with less to choose from in transmissions. I want to say 4 speed auto was all they had. Might do about as well in town as some of the Dmax pickups, but highway would be worse.

    21mpg in a suburban !!! I'm impressed. I don't think you'd beat that (with similar hauling ability) unless you went with a diesel, and a fairly efficient one at that. GM offered their 6.2 & 6.5L diesels in suburbans (1/2 and 3/4 ton) and tahoes up until the Duramax took over. Some of those (with right tranny, gears, etc.) would do well. In more modern diesels, I've heard mostly that Duramax and Cummins do a little better than the Fords, though the best mpg recorded in the logs for a big diesel pickup is in a Ford. I'd stay away from anything with a DPF (2007 emissions).

    There's plenty of tips around hear to stretch your mpg, but it sure helps to start with an efficient vehicle in the first place.
  18. phoebeisis

    phoebeisis Well-Known Member

    Thanks. Yes, I get mixed up by the diesels,since I never fool with them.
    You're right-those ebay vans have 4 speed ATs.


    PS I get almost exactly 21 mpg on the long 3000 mile all highway trips we take from New Orleans to Flagstaff AZ. I usually set the CC to 68 mph, but there is lots of road work(45 mph), some cities etc, so I would bet my actual road speed averages more like 62 mph or so. I bought it used 2.5 years ago-the hy mpg was a pleasant surprise.I get 14-15 in mixed city tanks.
    Last edited: Aug 11, 2009
  19. Silverado

    Silverado Member

    MPH or MPG? I'm spinning at 1900 rpm in 5th at 65 mph, but only getting 24 mpg.
  20. phoebeisis

    phoebeisis Well-Known Member

    30 mpg for that HUGE 4x4 brick would be pretty decent going DOWNHILL.
    Turbo diesels have a HUGE inherent advantage over spark motors. In truth for my needs-a big box to haul dogs and cats and humans-I only need 1/2 the power of the 6.6.

    A buddy of mine had the old 5.7 liter non turbo diesel in a 1/2 ton Suburban in 1985 or so.He got an honest 25 mpg on long highway trips back then. He had lots of problems with that motor, and the injection system, but it got great mpg.

    Silverado- hard to beat a diesel for highway mpg-or for towing-even with your 4.3.GM doesn't seem to put much effort in getting good mpg with the V-6 not sure why.The 5.3 usually all but matches the 4.3 when they are in the same vehicle.


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