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Discussion Starter · #1 · (Edited)
Very Very Disappointed in my 2008 Highlander Hybrid. It has about 60k and I drove it the last take 75% city and 25% Highway and only got 18.7MPG. Not good. We traded our 2009 Toyota Camry that would get 30+MPG in for this POS. Bad move. I even babied the gas pedal and only 18MPG. What can I do to increase this. What made me mad was the dash said the average is 22.6MPH, which I would kinda accept, but not 18.7!!!

What Should I do to fix this problem, reset ECU (how?) sell it and get the Camry back?:headbang:

I know that I will not get nearly the MPG that the Camry did, but though I would average 25 would be awesome.... Just changed Oil full synth. Tires are like new with the proper pressure. I have babied the tank and 18.7 that's it, should I take it in to get looked at???
 

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I can't help you with your specific vehicle's poor mileage but I can tell you there's something wrong. Why do I say this -- because my 2006 2WD just got 30 mpg average on a 3,500 mile trip, mostly highway but also lots of climbing (Yellowstone). In everyday usage I typically get 26 mpg at 75 mph and 28 mpg at 65 mph, and 33+ mpg in town urban driving. This is measured using a ScanGuage II and verified by calculating fuel consumption the old fashioned way, by dividing the actual mileage (based on GPs and road markers) by the fuel used (using same pump over multiple fill-ups). I keep tires 3 to 4 psi more than recommended. Initially I was gentle on the gas, accelerating smoothly and then backing off and touching the gas pedal again which seemed to trigger the hybrid to switch into battery mode, but these days I'm less fixated with babying the car because I'm getting acceptable mileage. I know on my 2006 that if the auxiliary battery is every allowed to discharge below a certain voltage this apparently affects the Idle Speed Control which can negatively impact fuel consumption, so perhaps have your dealer check if this can affect your 2008 (although I don't think it applies to your year).
 

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Very Very Disappointed in my 2008 Highlander Hybrid. It has about 60k and I drove it the last take 75% city and 25% Highway and only got 18.7MPG. Not good. We traded our 2009 Toyota Camry that would get 30+MPG in for this POS. Bad move. I even babied the gas pedel and only 18MPG. What can I do to increase this. What made me mad was the dash said the average is 22.6MPH, which I would kinda accept, but not 18.7!!!

What Should I do to fix this problem, reset ECU (how?) sell it and get the Camry back?:headbang:
Hi, I am sorry to hear that. This is one of the reasons I did not buy a HHL. I also read so many reviews about this issue and finally gave on buying one. Good luck
 

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Very many things would contribute to your mileage loss.
1. Since you bought it used, could it be the battery is getting bad?
2. Climate, how hot is your area? AC on all the time?
3. Tires and oil change
the list goes on.

What you can do is change the MFD to have the mileage bar and see what's can be improved when you're driving, keeping the bar above your average will improve the gas mileage.

Don't forget, this is a bigger and heavier car than your camry. Especially if it's a 7 seater. If you want to compare, compare it to the same category SUV, not sedan. If you want a better mileage hybrid than your camry, get a prius.
 

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Definitely something wrong with your hybrid. I have an all gas-powered HL and average 22 MPG, maxing out at 28 MPG at 65 MPH on the freeway. Has your mileage always been that bad or has it gotten worse over time?

BTW, newell21, your other thread in the 2nd Gen Highlander forum was merged with this one because Forum Rules do not allow for double and/or cross posting, but I did leave a redirect to this thread in the other forum.
 

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Very Very Disappointed in my 2008 Highlander Hybrid. It has about 60k and I drove it the last take 75% city and 25% Highway and only got 18.7MPG. Not good. We traded our 2009 Toyota Camry that would get 30+MPG in for this POS. Bad move. I even babied the gas pedel and only 18MPG. What can I do to increase this. What made me mad was the dash said the average is 22.6MPH, which I would kinda accept, but not 18.7!!!

What Should I do to fix this problem, reset ECU (how?) sell it and get the Camry back?:headbang:
i would recommand trying couple of things first before attempting the ecu reset. i would do a bottle of the redline fuel system cleaner with 10 gal. of gas. run it down beyond "0" milage range reading. then put a tank of premium gas try the babied it from this point forward, you will see your milage climb.
now there will be doubters and skeptics about using premium gas and how it will not be beneficial as the engine is not designed for it's intented use, i've personally tested and kept tract of the gas issue between regular and premium, i get an increased of 7-10% in milage using premium. so price p/g vs. mpg ratio wise, its a wash then why not give your car the better, cleaner gas to begin with. my 2cent.
 

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Discussion Starter · #7 ·
I bought this vehicle in Washington DC where there are hills and mountains. I drove it all the way back to Iowa where it is flat so I figure I should reset the ECU, would that make sense. Is the best way to pull the battery for 30 min?
 

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Regarding resetting the ECU, I don't know if this is the same as the ISC (Idle Speed Controller) but if it is then disconnecting the battery for 30 mins won't help. The problem with this approach, as I understand it, is that the ISC needs to be reset by the dealer once voltage of the auxiliary battery falls below 7v (don't quote me on that number). There is a way to do it yourself but I think a bit risky - search this forum for details.
 

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we got 29 mpg on a 800 mile trip the other day, 06 Hihy 67k total, only thing to go wrong so far was the inverter and warranty covered it.
 

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I've noticed that mileage has improved now that temps are in the mid 60's. Recently I been driving a combo of highway and urban roads and averaged 33.4 mpg (accurate).
 

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Is the hybrid system even working? On the display do you see energy moving from the traction battery to the wheels? It will always do this when starting from a stop. When everything is warmed up and you accelerate gently with the speed below 40 mph you can usually keep it on battery all the time.

What is the charge state of the traction battery? Is it decreasing and then charging back up.

FYI, the computer display for MPG is about 5-8% optimistic
 

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Declining gas mileage

I bought a 2007 Highlander hybrid from an Arlington Texas Toyota dealership about 10 days ago. As I drove it home, a 40 mile trip, the mileage averaged about 25.5 MPG on the dash readout -- kind of disappointing, because I thought the trip being 10% city would boost the average to maybe 28 or 29 mpg.

After I refilled the tank, drove it about 290 miles, and checked the mileage, it was down to 23 mpg even though I was hitting about 25 mpg according to the display. But now the last two or three trips, the mileage according to the display is 19 and 19.5 MPG. (I haven't refilled yet to do the actual mileage math for the current tank)

Full disclosure – I live in Texas, and we are in the middle of a typical stretch of 100° days, so the AC is always on. Also I weigh 300 pounds, but that's also what I weighed when I bought it, so that can't be blamed for the MPG drop from 26 to 19. I wonder that if the dealership had premium gas in it, would my two refills with regular gas cause that big of a decline? And if so, why would the mileage decrease again from the first tank of regular gas to the second?

I'd appreciate any thoughts.
 

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FWIW, I have been tracking my mpg especially when starting a long trip. Some info: I have a 2006 2 wheel drive, new Continental Eco tires (mileage dropped 2 mpg from OEM MichX), I usual have a/c (Florida), I usual drive freeways at 68 to 73 (rarely higher), a 50/50 mix of town and freeway. I fill with higher grade because of pinging (pre-ignition). I'm averaging 27mpg highway and 30 around town.
 

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Hard to gauge but I'm guessing the slightly less efficient Continental Eco tires, at least while they're new, with more rolling resistance, offsets the slightly better mpg achieved from higher performance 89 or 92 octane.
 
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