I have a silver 2007 HCH II that I purchased new in february of 2007. In the beginning I was able to achieve pretty decent gas mileage somewhere in the low 40's to high 30's while driving exclusively in Atlanta stop and go city driving.
Over the last 2 and a half years my mileage has seriously slipped and now my computer reads not greater that 30 mpg. In fact I can barely get it to go over 29. I am filling up about every 250 miles which is just crazy. I have taken the car to two different dealerships and have been told that this is normal mpg for city driving!
I am at a total loss to as to how to get them to do a serious evaluation and help me to determine what may be happening...does anyone have any ideas? Here are some facts:
-37,000 miles (I have taken several long trips, otherwise is is about 11,000 per year)
-New tires that the dealer put on about 5,000 miles ago. They are Toyo Extensa which I now know are not LRR tires. I expected a mileage hit, but not 25++%. I asked for LRR and trusted them, but apparently they did not care to listen and I didn't think to do the research BEFORE i let them put them on. Honestly I didn't think I needed to since I was pretty clear about what tires I wanted.
-I use high mileage driving techniques all of the time. Coasting, no jackrabbit starts, etc.,
-I get a lot of battery re-calibrations, at least 3 times a week and more if I use the climate control.
-All maintenance is up to date and I have been diligent about keeping it that way
-I rear-ended someone after two months of ownership and did some pretty extensive damage (needless to say that was a BAD BAD BAD day). However, I did get fine gas mileage after that accident so that does not seem to be the cause.

Thanks in advance for the help. I really am getting to the point where I sincerely dislike this car even though it is the car I dreamed about owning. I want to love it, but right now its underpowered and get horrible gas mileage. I can live with underpowered if I am getting in the 40's, but not the 20's...Please help!

Hmmm... let's see...

1. Check your suspension control arms and alignment
2. Check your engine air filter
3. See if you're using 0W-20 oil – some dealers use the wrong weight
4. Increase your tire pressures to 40+ PSI
5. Get the best LRR tires – it's worth $$$ just to love your car again
6. Consider getting your software updated

Steve Villatoro
www.stevenvillatoro.com

Former hybrids: '02 Insight; '07 Camry Hybrid
Former microcars: '08 smart; '57 BMW Isetta 300

I had my control arms checked and the dealer said they were fine and did not need to be replaced. I brought in the paperwork that was posted here and elsewhere to show them, but they said it was not needed on my car. Just had my oil changed at another dealer about 500 miles after my last oil change to make sure the right oil was in it and that the levels were okay. The air filter was changed at that previous oil change. The alignment was checked when I had the tires changed, but I can have it checked again. My only problem with tires is that these are pretty new and I just don't want to spend the additional money on new tires right now since I just made this investment. But if that is what is causing the dramatic decrease in FE, then I guess that is the answer. It just seems so gradual and such a steep decline for it to be tires. I suppose I wish that dealers were more responsive and interested in helping to troubleshoot these cars rather than say they just get bad mileage so live with it....still falling out of love with Honda and hating it.

Everything Steve suggested plus get your 12v battery checked out.

Jess

The symptoms of sluggish performance, frequent recalibrations, and much reduced mileage point to issues with the IMA system and the computer controls which govern its operation. As others have mentioned, there have been software updates which address these issues. Also, a weak 12 volt battery can sometimes be at the root of irratic IMA behavior.

At the moment you are essentially driving without the benefit of the hybrid system.

I really doubt your new tires would explain more than a 2-3% drop in mileage; and this tends to decline as they get worn in.

You need to find a dealer who is prepared to give your concerns serious attention.

Good luck!

Dream'R,
Thanks so much. That will help me when I go back to the second dealer. I really want the car back to performing the way it originally did! I just get so frustrated when the dealers just brush me off and say, that the city mileage is normal...thanks again for the direction!
Todd

I wouldn't think it's the tires causing you a ~25% hit. I put on aggressive studded snow tires a few weeks ago on heavy steel rims and have only taken an 11% mpg hit.

Good luck finding the problem--how frustrating!

We've got exactly the same problem with out '06; gas mileage was in the high 30's - low 40's and this year it's dropped to the low 30's or even high 20's. In addition, performance has been terrible, the main battery won't fully charge and intermittently resets.

We've been in and out of the dealer for seven months with a "we drove it and it seems OK" response, and I finally went medieval on the service manager - this is at Scott Robinson Honda in Torrance, where the Honda fleet cars are serviced - and they discovered that all the software in the car was outdated, and that there were incompatible versions in the various control units. They reflashed everything, and performance has improved, mileage has improved (slightly - now 33.6) but the battery still regenerates and won't fully charge.

Just took it back, they can't find any codes, and so I just talked - again - with the service manager.

If we find a root problem, I'll be happy to share it. otherwise we should at least all connect and talk to Honda together...

Several responders have mentioned ailing 12 volt battery, and the impact that might have. We've got the '06 and I finally bit the bullet, our 12 volt is being swapped out today. It had 2 depletions in the past, and recently sat in a body shop for close to a month. On receipt after that last stint the indicator window showed red dot in clear surround, which indicates charging needed. I managed to restore it to showing blue ring, by a combo of overnight charging sessions and driving, but I suspected it was still borderline, considering it's age/history.

My understanding is a weak 12 volt causes the IMA battery to have to do more "menial" voltage supplying, which in turn can lead to more depletion, more recal's, less assist, and ultimately: poorer mileage. Anyway, I'll post if I see any improvement with the new 12 volt.