Arrgh! Summer Mileage

Discussion in 'Honda Hybrids' started by jmelson, Jun 23, 2009.

  1. jmelson

    jmelson Well-Known Member

    Well, I thought was doing well breaking in my 2009 HCH-II and working up to ~52 MPG using mostly E10 gasohol in mixed driving to work and back. Suddenly, it has gotten much worse, I was only able to do about 46 MPG today. It is hot here (St. Louis, MO) but I do park in my garage at home and a covered garage at work, so the car doesn't sit and roast in the sun. I use the AC lightly, usually set the inside temp around 78F.

    This is really bugging me. My 2008 HCH-II that got wrecked was up to 56 MPG at 3300 miles, when it got totalled. I now have 6000 miles on this 2009, and have never gotten over 52 MPG on it (tank average). Is this all from the AC use, or just the heat on the hybrid system? Summer gas formula? I definitely have not seen an SoC recal, although I have seen the SoC drop to 4 bars now and then.

  2. hunter44102

    hunter44102 Well-Known Member

    What about tire pressure? It seems to make a big difference in mileage in my HCHII. I usually make sure I have at least 37-39PSI per tire.

    I had a nail in my back tire and the pressure was down to 25PSI, and my mileage was lower for a few weeks
  3. Taliesin

    Taliesin Well-Known Member

    Did you just recently start using the AC?

    On many vehicles, it doesn't matter what you set the temp or other settings at. If the AC is on, the compressor is on (and that is the big drain on FE).

    The temp is adjusted by adding heat to that cooled air. It's much more efficient to manually cycle the AC instead of letting the lazy computer do it.
  4. msantos

    msantos Eco Accelerometrist

    Hi Jon;

    When it gets hot, the mileage goes down for sure. The question is by how much and whether something can be done about it. It looks like you are doing many things right already but there are few more that may also be up your alley. For instance:

    - Take the tire pressures up a bit more.
    - Have a look here just in case: "HCH-2 AC tips"
    - Wheel alignment!!!!

    On the subject of wheel alignments: I always have the dealer perform a wheel alignment at the time of purchase on any vehicle shipped from Japan. No exceptions for me and I always recommend new owners ask for the same.
    In every single instance, correctable deviations were found and handled before I drove the car off the dealer's lot. I am definitely not joking and I suspect the boat anchor you are dragging may be due in small part to that. I hope I am wrong this time.

    Funny thing is that some folks have told me the minor skin/styling changes that were applied to the 2009 had a slight impact on the vehicle aero-dynamics and FE compared to the previous years. I have not verified that in the 2009's I have driven.... mainly because I never take them to higher speeds anyway!? What speeds to you usually drive at?


  5. Taliesin

    Taliesin Well-Known Member

    Looks like an excellent article, and would be well worth your time.

    You can ignore what I said earlier and just follow this if it's an AC issue.

    And yes, it's been getting very hot (and very humid) in our area (50 miles east of KC here).
  6. cyclic

    cyclic New Member

    Don't think wheel alignment will be an issue on a new 09.

    I am getting 55 MPG (70 MPG Imperial) on my 09 HCH. I only have 1400kms on it, however on the west coast we are only about 70 degrees right now. I put my tires up to 40 psi.
  7. jmelson

    jmelson Well-Known Member

    I just checked it, I have 44-45 PSI in all tires. So, that's not it.

  8. jmelson

    jmelson Well-Known Member

    I am NOT going to go above the max pressure printed on the sidewall. Actually, a couple tires are 1 PSI over the 44 limit, I figure I can get away with that.
    I've already read it several times, thanks. But, I don't think I can do much better than I already am.
    Very interesting thought, I'll see what I can get them to agree to as it is about due for the first oil change. I did run over some road debris, I think it was half of a truck leaf spring, last week. I t made a big clunk underneath. Could have affected alignment. Unlike the dealer of my first HCH-II, this one seems to be one of those high-volume in-and-out sorts of places that might not agree to any work not totally necessary. I fear I'd have to pay full price for a 4-wheel alignment, with typical dealer markup in might be over $200.
    My commute to work is a mix of 30-35 MPH sub-urban streets and a bit of 55 MPH highway. I generally keep it between 50 - 55 MPH there, and DWL. So, I was expecting a LOT better mileage than this. There's a long light getting out of work, so I usually FAS there.

  9. msantos

    msantos Eco Accelerometrist

    Hi Jon;

    I did not know your actual tire pressures, but the ones you're sporting should give you plenty of MPG headroom. The MPG you are getting does not show it at all.

    Your speeds are excellent as well.

    How about your glides? Are they short lived compared to your 2008? Does the car track straight? How are you tires wearing?


  10. jmelson

    jmelson Well-Known Member

    I can't glide very far most of the time, there are little hills EVERYWHERE. But, I can't DETECT any difference in glide length in the 2009. There is a nice, gently hilly road with an overall down-grade that I can do really good mileage on coming home. On some of the small up-grades I can get over them with just a little assist motor and no ICE, and otherwise just short blips with the ICE.
    Also, there's a nice flat section of the highway where I can set up an economical cruise at about 60 MPG. But, all of this is in short sections, with bigger hills, traffic, and other mileage killers all along the drive. But, I was OK with the slightly better than 50 MPG I was getting a few weeks ago, and I've been using the AC since mid-May, I think. St. Louis definitely gets hotter before Canada.

    The car tracks as straight as I can tell, so there is no obvious misalignment detectable at the steering wheel. I will try to examine the tire tread, but I've never been real good at detecting the "feathered edges" that the experts can spot from 20 feet away.

    When I was getting 56 MPG with the 2008 HCH-II, I was using a different route, as our local highway was closed for total reconstruction. I will have to run that route to see what mileage I can get now. A few MPG won't get me to drive city streets with lots of stop lights, but 10 MPG might make me go back to the streets.

  11. msantos

    msantos Eco Accelerometrist

    Can you check the engine oil level? An overfill will kill your FE.

    I agree. Trying your old itinerary again may be the best yardstick.
  12. jmelson

    jmelson Well-Known Member

    The oil has never been changed, or filled. It certainly shouldn't be going UP! Well, that WOULD explain where the gas is going, of course. I am about due for the first oil change.

    But, I was getting ~52 MPG several weeks ago on this daily commute. The only thing I can think of that has changed is temperature, and a different tank of gas.

  13. Yaris Hilton

    Yaris Hilton Half a Bubble Off Plumb

    Exactly. That's a horrible way to regulate the air temperature, by chilling it to the max with AC and then mixing in heated air if you don't want it fully cold!
  14. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    I'm pretty sure the newer hondas, like this one, cycle the compressor on and off as needed. Much more efficient this way.
  15. jmelson

    jmelson Well-Known Member

    Well, just to expand on previous comments, when I picked up this vehicle, it had 4 flat tires, and the TPMS was going off every minute I drove! They took it out for a "test drive" before turning it over to me, so I assume it was doing that for them too. All 4 tires were at or below 25 PSI, I think one was at 18! I took it straight home and pumped them up properly.

    So, I have the GREATEST doubts this dealer will be willing to do a complementary 4-wheel alignment. With my last HCH-II and a different dealer, they refused to do an oil change until the wrench light came on - I never got to drive that one long enough for that.

    I am coming up for an oil change, and I got a notice for what sounds like a software update related to extreme cold operation, so I will mention this poor mileage to the dealer, but I suspect they will blow me off as a nut. "Hell, you're getting better than EPA mileage, what the HELL are you complaining about?"

  16. msantos

    msantos Eco Accelerometrist

    Hi Jon;

    I think you are right. Unfortunately some (if not most) dealers will do just that. Brush you off. Anyway, make sure you at least get the right oil and the right amount poured in because the wrong oil will knock 10-15 MPG right off the top. ;)

    With regards to the wheel alignment... that is a tough one. It looks as if your only option is to find a shop that will give you a quick and inexpensive verdict on the alignment!?
    Alternatively, you can always wait a bit until it is time to do one. Most "in the know" recommend an alignment on a regular basis perhaps every 2 years or even sooner depending on the road quality and mileage. In my view this is a good policy since an alignment is still cheaper than a full set of properly balanced tires not to mention the erosion in fuel economy.

  17. hunter44102

    hunter44102 Well-Known Member

    My honda dealer just sent a flyer for a $59.95 all-wheel alignment. Not sure if this is a good price, but it doesn't sound too bad
  18. psyshack

    psyshack He who posts articles

    We have also took a bad hit concerning summer temps and A/C on the 09 HCHII.

    Back when the temps were in the 80 to lower 90's and we used the A/C on the hwy set 78 to 82 I could get 56 to 58 mpg out of the car running 55 to 60 mpg and using basic tactics. Now that temps have went up to 98 to 102 I have not been able to get much above 52 mpg out of it on our daily grind in the afternoons. The morning commutes in 78 to 82 temps It's a no brainer to get into the lower to mid 60 mpg area.

    The A/C seems to be really dragging the already under whelming power way down. Battery management is easy for me. I think it troubles the wife a bit. So I'm able to keep 5 to 8 bars easy concerning the battery.

    I think its high intake air temp causing the problem myself. I've noticed the MZ3 getting a tad sluggish of late when I drive it. Then it dawned on me I had not put it's OEM cool air intake back on. While it does not have the WAI tube on, it's still drawing hot air in the air box from under the hood. HCHII does this by default! Even if we sweat it out and go with no A/C, windows cracked and the dash blowing outside air the car is still sluggish. It also becomes harder to SAMBA and SAHM. It will still glide and such. I don't fas it and even glides seem kind of worthless if you can make it SAMBA or SAHM. I don't think it will glide or fas as good as the awful Ranger. I need to do a coast down test with it.

    In short,,, I think its high intake air temps in combo with A/C.... I'm seeing it also....
  19. jmelson

    jmelson Well-Known Member

    Well, I probably wouldn't be complaining about 52 MPG at near 100 F. We've had a combination of upper 80s to upper 90s and I'm getting anywhere from 42 to 47 MPG, and can't get above that, in mixed city/hwy driving. A couple months ago, when I reset the trip odometer after a gas fillup, I could maintain 75 MPG for a day or so until I got stuck in traffic or whatever. Maybe it is all temperature, then.

    I took two highway trips, and ran rather fast 65 - 70 MPH, and was getting 47 MPG and thought that was mediocre, but I had a ton of stuff in the car, and used cruise control, too. Now, I'm driving myself to work in an empty car, and getting 47 MPG on city streets and such, with careful high mileage efforts.

  20. kgenaidy

    kgenaidy Well-Known Member


    I'm a newbie and have been watching this thread with great interest. I have an 09 HCHII and live in the DFW area. I bought the vehicle in January of this year and use the vehicle primarily for commuting ... 30 miles to and from work ... with mix of city and highway driving.

    This week I have been only able to achieve 52.38 mpg on this weeks "tank" of gas due to the heat. I have tried to adopt the using AC w/minimal FE loss (keep it set at 84-86 or in auto mode) along w/other basic techniques discussed in this forum.

    In more modest weather I am able to usually get 54-57 mpg on the weekly tank of gas.

    Being a newbie ... the hardest thing to adjust to with this heat ... is the almost daily "afternoon" battery drain and associated recal. On the trip home I'm initially faced w/stop and go and a long gradual grade. By the time the car "warms up" ... damage has been done to SOC and we're in recal mode.

    I guess this is my long winded way of saying I am also seeing similar results to what others have shared in this thread.

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