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'04 APS'ified STi
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Discussion Starter · #1 ·
We currently have about 400 miles on our 2010 HiHy and are on our second tank of gas (the dealership had to transfer it about 100 miles from another dealership before we took delivery. We are upgrading from a 2006 in which we got about 22-25mpg with normal, non-grandpa driving.

So far in the 2010, we're at about 18 mpg (on the high end). I've been driving it in nothing but econ mode and really babying the crap out of it, and I'm still only getting about 18mpg. I don't know if there might be something wonky with the fuel mapping, but I'm definitely not happy with this mileage, especially based on what other people are reporting (25-30 in some cases). Hell, I'd be fine with 22-25 just like we had in the 2006 but I've not gotten anywhere close to that.

Some things that I'm thinking might be having an effect:
  • 2/3 of the last tank (the full tank the dealership gave us), the gas cap was loose (they left it loose).
  • After I realized the above, I cleared the codes with an OBD-II scanner. Maybe this causes the ECU to have to re-learn to some extent?
  • Maybe the car hasn't learned our driving habits and is still in the initial learning phase. Would this have this big of a hit on mileage though?
  • Since our last fill-up (and having a tank with the gas cap actually tight, most of our trips have been short ones - 10 miles max. There is a good amount of stop & go, but again, I would think this would be ideal for the hybrid rather than translating to piss poor mileage.

I don't really know what to make of this. I'm going to be grossly disappointed if this is what I end up with long term and I go from the 2006 giving an average of roughly 22mpg to having a 2010 giving us roughly 20% lower fuel economy.

Did anyone else experience this during the first month+ of ownership? I believe Virginia has a law that allows 30 days to return a car, though I could be remembering incorrectly. We were so happy with the 2006 that I thought the 2010 would be a slam dunk. I'm happy with the changes they made to the next model, but if this is normal mileage ... :disappoin

Here's a snapshot of the last few trips:
 

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2008 Highlander Base
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35,702 Posts
Some observations and/or suggestions based on what you've posted:

1. What tires do you have on your Highlander? They're definitely not all the same, and roll resistance can be significant. I've seen improvements in MPG approaching 10% with tires that have lower roll resistance.

2. Unhook your battery for at least 15 minutes (some sources recommend 30 minutes), to clear the memory in your ECU. Hook the battery back up, then drive in a normal, economical manner (not saying you're not already) so that the computer can relearn your shift points.

3. Give your Highlander time to break in. Six months should do it. I saw nearly a 10% improvement in mileage between when my HL was new and over six months old.

4. Change the location where you're purchasing your gas. Again, I've logged as much as a 15% drop in mileage (10% with my Highlander once upon a time) due to "bad gas," typically off-season blends sold at independent and other stations.

5. What is the breakdown of your mileage, ie., % driven in the city versus % driven on the highway. Also, in the city, how long are your trips both time and mileage? How fast do you drive on the freeway?
 

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'04 APS'ified STi
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Discussion Starter · #3 ·
Some observations and/or suggestions based on what you've posted:

1. What tires do you have on your Highlander? They're definitely not all the same, and roll resistance can be significant. I've seen improvements in MPG approaching 10% with tires that have lower roll resistance.
I have the stock Toyos. They're the brand new tires that came on the vehicle with dealer tire pressure.

2. Unhook your battery for at least 15 minutes (some sources recommend 30 minutes), to clear the memory in your ECU. Hook the battery back up, then drive in a normal, economical manner (not saying you're not already) so that the computer can relearn your shift points.
I considered resetting the ECU but shouldn't the ECU be basically "clean" since it's essentially right from the dealership?

3. Give your Highlander time to break in. Six months should do it. I saw nearly a 10% improvement in mileage between when my HL was new and over six months old.
I'm all for breaking in, but 6 months is ridiculous to get to optimal fuel economy. I'm not saying you're not right in this suggestion, I just find it surprising / disappointing.

4. Change the location where you're purchasing your gas. Again, I've logged as much as a 15% drop in mileage (10% with my Highlander once upon a time) due to "bad gas," typically off-season blends sold at independent and other stations.
I'm getting my gas the same place that I've always gotten my gas (it's where I got the gas for my 2006 HiHy, so I'm not really suspicious of this being the cause).

5. What is the breakdown of your mileage, ie., % driven in the city versus % driven on the highway. Also, in the city, how long are your trips both time and mileage? How fast do you drive on the freeway?
Right now, we have only about 400 miles on the car, approximately 100 of which was highway from the original dealership to the one we purchased the car (the dealership we bought from had to trade with another to bring it in for us so they had to drive it about 100 miles). So we only have about 300 of our own miles on the HiHy. Having said that, however, I'd say that maybe half was highway and half was in town within, say, 20 miles from home going to various stores, school, activities, etc. On the highway, we typically run between 60 and 75 (again, nothing different from our '06 HiHy and the new one).
 

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2009 THH
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21 Posts
Gas milage

Your short trips are probably the main cause of your low milage.

Try switching to a non-ethanol gasoline -- you should gain 3.3% milage by doing so.

Was your previous vehicle a hybrid? The way hybrids get better milage is primarily through regenerative braking which is less likely to occur when you stop quickly.
 

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'04 APS'ified STi
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Discussion Starter · #5 ·
Your short trips are probably the main cause of your low milage.
I gave this some thought, but isn't this where hybrids are supposed to thrive? In stop / go traffic? Long trips suggest highway driving, and the highway isn't really the sweet spot for Hybrid performance. Or are you saying that with short trips the vehicle isn't really getting warm enough to get to optimal fuel economy?

Try switching to a non-ethanol gasoline -- you should gain 3.3% milage by doing so.
I'd *love* to do this. Unfortunately I'm not aware of a single station in my area that doesn't have the "this gas contains up to 10% ethanol" sticker on it. Is there some resource for finding non-ethanol gas?

Was your previous vehicle a hybrid? The way hybrids get better milage is primarily through regenerative braking which is less likely to occur when you stop quickly.
It was - and I have been driving this one MUCH more conservatively than I drove our '06 HiHy - not to mention the fact that I have had Econ enabled (not available in the '06).
 

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Discussion Starter · #6 ·
I think I might have discovered the culprit (and maybe it does necessitate an ECU reset). The car originally came from an area outside RFG (reformulated gas) areas. In my county (and all neighboring counties best I can tell), E10 is required and I'm not going to find E0. My guess is the new car, being driven 100 or so miles on "real" gas learned that particular fuel and then it was given E10 locally, likely confusing it or screwing with the already-learned mapping. I could potentially just give it time to re-learn or force a reset. I read on this forum in a couple places (here, for example: http://www.toyotanation.com/forum/showthread.php?t=326854) that disconnecting the battery could lead to issues with the ISC so I guess resetting the ECU is a last resort (at least by lifting the battery lead, that is).
 

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08 Highlander Hybrid
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When they switched here to the ethonol blend I lost 4-5 MPG in my 08.

Sucks and all for taxes... think about it, 1) takes more energy to produce, 2) the consumer burns more fuel (= more tax revenue), 3) food proces rise... Everything a politician loves.
 

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I gave this some thought, but isn't this where hybrids are supposed to thrive? In stop / go traffic? Long trips suggest highway driving, and the highway isn't really the sweet spot for Hybrid performance. Or are you saying that with short trips the vehicle isn't really getting warm enough to get to optimal fuel economy?
Warming the engine takes energy which causes a drop in fuel efficiency for short trips -- non-hybrids also have this problem.

I'd *love* to do this. Unfortunately I'm not aware of a single station in my area that doesn't have the "this gas contains up to 10% ethanol" sticker on it. Is there some resource for finding non-ethanol gas?
10% ethanol should at most cause a 1 mpg drop. The gasoline that it's mixed with can be lower quality, so try premium or a different brand. Premium gasoline may not be worth using because of the price, but look at it as an experiment.

It was - and I have been driving this one MUCH more conservatively than I drove our '06 HiHy - not to mention the fact that I have had Econ enabled (not available in the '06).
I am not sure that driving conservatively helps a lot since the regenerative braking recovers much of the energy from braking.

Open windows will increase drag on the vehicle reducing mpg.
 

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2008 Highlander Base
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I have the stock Toyos. They're the brand new tires that came on the vehicle with dealer tire pressure.

Remember that new tires also have a breaking in period of around 500 miles, and they'll produce lower mileage due to increased friction with the road.


I considered resetting the ECU but shouldn't the ECU be basically "clean" since it's essentially right from the dealership?

You never know how many dealership people may have driven your Highlander and how they drove it. What was your mileage when you picked it up? Nevertheless, it certainly won't hurt anything to reset the ECU and have it relearn your shift points.


I'm all for breaking in, but 6 months is ridiculous to get to optimal fuel economy. I'm not saying you're not right in this suggestion, I just find it surprising / disappointing.

Wish I could offer a different number, but 6 months is pretty much it. You're dealing with moving parts that fit don't fit perfectly together and need time to wear a bit and reduce friction, including your tires.


I'm getting my gas the same place that I've always gotten my gas (it's where I got the gas for my 2006 HiHy, so I'm not really suspicious of this being the cause).

Cool! That's a big help. :thumbsup:


Right now, we have only about 400 miles on the car, approximately 100 of which was highway from the original dealership to the one we purchased the car (the dealership we bought from had to trade with another to bring it in for us so they had to drive it about 100 miles). So we only have about 300 of our own miles on the HiHy. Having said that, however, I'd say that maybe half was highway and half was in town within, say, 20 miles from home going to various stores, school, activities, etc. On the highway, we typically run between 60 and 75 (again, nothing different from our '06 HiHy and the new one).

After reading that I'd recommend resetting the ECU. The first 100 miles was driven by a dealership employee who drove it in an unknown manner, which I doubt was like the "little old lady from Pasadena."
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'04 APS'ified STi
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Discussion Starter · #10 ·
As far as resetting the ECU, no concerns with mucking up the ISC?
 

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2008 Highlander Base
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There are no issues I'm aware of regarding resetting the ECU via battery disconnect. Never had any problems myself with idle control, etc., everything runs fine.
 

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As far as resetting the ECU, no concerns with mucking up the ISC?
I haven't heard of any concerns on the 2nd gen Hihy. On the 1st gen Hihy, there is a TSB indicating that battery disconnect can cause ISC issues, and that dealer reflashing may be necessary after battery disconnect.
 

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'04 APS'ified STi
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Discussion Starter · #13 ·
Just an update. After driving a bit more (and getting out of the quick here-and-there trips within 5 miles of home), my mileage has gone up to between 22 and 27. 27 was the best I got on a trip that was surprisingly mostly highway and about a 50 mile drive.

For those interested:
Total odometer: ~1000 mi
Tire Pressure: recommended 33psi
Gas: nothing special - just Safeway brand 87 octane regular gas with E10 (I don't have a choice due to where I live - DC metro area).
 
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