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HELP! My HiHy is a pig on gas!

Highlander hybrid mpg thread
I am consolidating all mpg threads for the last 2 years into single dedicated thread. I am positive any new owner question or concern can be answered by simply reading through dozens of posts on this topic.
Please, keep your mpg Why-s to this thread, unless you read it all and clearly your situation is somehow not answered or discussed before.




Hello

I live in NS. I have owned my 08HiHY since Sept 08. It has 18000km. I have NEVER had great mileage ( the best fillup avg mileage is 9.1L/100km (26mpg). I drive 90% in the city. Rolling hills, not too steep.

Any time I pushe the gas pedal, my mileage goes way down and its hard to recover with the bat. I try to feather the pedal and coast w/ bat but any acceleration causes ice
I drive VERY conservatively. In the winter, I can't do more than 12L/100km (19mpg)

I tried the ECON and there is almost no difference in mileage.

Is my HiHy a lemon on gas? Or am I doing something wrong.
 

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Your HiHy is performing normally (unfortunately).

Try resetting the car by disconnecting the negative terminal from your 12v battery for a few minutes.

Many people found that to correct the issue.

Winter isn't really that great for these cars in terms of fuel efficiency.

I live in the Ottawa area, and find that I only get 22mpg average in the winter.

Still better than most other vehicle this size. I'll install a block heater this week, and see if it makes a real difference or not.
 

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Discussion Starter #3
Thanks. but how does that compare to the regular highlander? THe EPA estimate is way off (7.7city/8.1hwy) compared to my 9+ in the city. How does disconnecting the neg terminal help?
Also, I have to run with my heating to "max cold" in the winter, otherwise the ICE always runs!
 

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Discussion Starter #4
There are people in this group that get mpg's in the 30's? How do you guys do this? Is there an ideal way to drive the HiHy? What about accelerating briskly then coasting compared to gentle acceleration?
 

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There are people in this group that get mpg's in the 30's? How do you guys do this? Is there an ideal way to drive the HiHy? What about accelerating briskly then coasting compared to gentle acceleration?
Believe it or not your HH is behaving normally. The hybrid part of the drive train does very little in cold weather. In fact, it needs almost an hour at highway speeds to warm up and contribute to the economy. I have seen this on my own 2008 both this winter and last winter. When the weather warms up to ~10-12 degrees C on a consistent basis you'll see an improvement to ~25-27 mpg. Every winter I average 20-22 mpg. In the summer 24-26. FYI I do 75% city and 25% highway mileage.

See my post in this thread which has a mpg graph http://www.toyotanation.com/forum/showthread.php?t=329558
 

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Below is the gas mileage of my Highlander Hybrid over the last 4 years compared to the daily outdoor temperature averaged over each tank of gas. The pink is the MPG and the Blue is the outdoor temperature (Chicago area). You can note the strong relationship between temperature and gas mileage per tank.

My lifetime gas mileage for this vehicle is 27.35 MPG using 1229 gallons over 33,615 miles.
 

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Looks like I need to figure a way to warm up the critical components such as differentials, tranny, battery, mg1 and both mg2 to maximize fuel economy for our climate.

I wonder if anyone has tested this optimization technique?
 

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Don r,

Your charts are very informative and clearly show the effect of temp. Perhaps that's why here in Florida, despite this winter's unusually cold temps, below freezing a few nights but warmer during my typically driving hours, I'm averaging 30mpg with a mix of highway and urban. In fact on occasion I have got 35 with just local streets. Anyhow, your record keeping is much appreciated.
 

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Yes, no savings compared to regular highlander in the cold.

I see the same thing: 19-22 mpg around freezing in the city/suburbs. One thing I discovered is that tire pressure really makes a big difference. My tires were 31 psi in the cold, at 36 psi I am getting 3-4 mpg more driving the same routes and distances. Econ doesn't do anything. This is a Jan 2010 HH. The best I ever got is 25 mpg highway so far with one person in the car.
 

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Believe it or not your HH is behaving normally. The hybrid part of the drive train does very little in cold weather. In fact, it needs almost an hour at highway speeds to warm up and contribute to the economy. I have seen this on my own 2008 both this winter and last winter. When the weather warms up to ~10-12 degrees C on a consistent basis you'll see an improvement to ~25-27 mpg. Every winter I average 20-22 mpg. In the summer 24-26. FYI I do 75% city and 25% highway mileage.

See my post in this thread which has a mpg graph http://www.toyotanation.com/forum/showthread.php?t=329558
+1

Seems most owners are not informed of this before purchasing their hybrids, and that's regardless of Toyota or other manufacturers from what I've been reading.
 

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Just did a 600 ish mile highway run, averaged 22mpg going there, and 28mpg coming back same day.

Cruise Control speed both way was set at 75 mph.

Overall average reported was 25 mpg

Temperature Range: 37 to 47 oF

For the Metric Speakers:

Just did a 1000 ish km highway run, averaged 10.7 l/100km going there, and 8.4 l/100km coming back same day.

Cruise Control speed both way was set at 120 km/h.

Overall average reported was 9.4 l/100km

Temperature Range: 3 to 8 oC
 

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I added a circuit that spoofs the engine temp when its cold so that the computer thinks the engine is warmer than it really is. Has had a big impact on my mpg, but still it works better in the summer. I know others who partially block the rad to keep the engine warmer in the winter.

The key to good mpg is to get the engine to turn off when it isn't needed, and when its cold it doesn't turn off so easily.

I love the temp vs mpg graph, displays quite well what I've come to understand about the car, I haven't recorded much, but I think the graph is about right.

There are a lot of differences when it's cold ve hot. For instance: below freezing, the engine always comes on in reverse. Above freezing , it may not.

The car gets it's best mpg vs a regular car on surface streets below 65km/hr, in warm weather. On the highway or in the cold the savings are much smaller. Also short trips don't work out well.

My world record trips are in the 50mpg range, a more typical trip with carefull driving is in the 40mpg to 30 mpg range, my wife usually gets 25mpg, on a cold day I have gotten as bad as 12mpg.

Tips for getting the most out of your Hyhi:
Seat heaters, AC, Cabin Heat, and or defrost (even radio): These will tend to keep your engine running even when you are stopped. If you want better mileage, you must turn these things off and only use them when you are accelerating.

During startup you can get stuck in "mode 3". This occurs if the car has warmed up but you haven't stoped at a trafic light for a period of longer than 10s, (in colder weather seams to be up to 35s). You must learn to recognize mode 3, and pull over and park for a bit to break into full hybrid mode. Mode 3 will crush your mpg. Full hybrid mode allows 40mpg with min effort. I usually use almost as much gas "warming up" the car as I do in the rest of the trip.

Accelerate progresivly faster. Start out smooth and slow, but press the pedal steadily more until you get to you target speed. Better to press hard for a few seconds that spend a lot of seconds on the gas not accelerating enough. The speedometer needle should move steadily upward. Don't gun it at the start, but by the end of an accel I'm usually pressing more than I would in a regular car.

Coast on neutral bat usage, don't let it regen, don't use bat. (or at least try only to use the amount you put in through regen braking. If the engine has to cycle to rechareg your bat you will blow a lot of mpg)

De-accel in mid blue. If you feel your brakes "hiccup" (maybe the're fixing this in the recalls?) that's your car switching to regular brakes. Lift you foot and start over to force continued regen. As you get slower you must brake harder to keep the regen going and your real brakes off.

Still my favourite part about this car is sneeking up behind people walking in parking lots.
 

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Thanks for the thorough description of your driving technique. It seems I've subconsciously being doing what you describe and because I'm in central Florida which is normal warm (except these past few months!) and flattish terrain my mileage in urban driving is typically averaging above 30 mpg. I'd like to know more about the circuit spoof you mentioned that fools the engine temp sensor - can you expand on this? TIA
 

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Hmm...a bit scary! It's been a while since I've dabbled with breadboards but probably know enough electronics to have a go but first let me ask the gurus on this site a few questions. Reading the links it's not clear whether this mod is a set-it-and-forget-it or if it needs continuous pot tweaking and disabling based on seasonal changes in ambient temps. Will running on elec motor for, say, 2 or 3 miles drain the battery such that ICE will start for recharge. Is it worth the risk of voiding warranty in view of the fact I'm getting pretty reasonable mileage around town and rarely go anywhere cold if i can avoid it, and in central Florida ICE cuts out when coming to a halt after a very short 1 mile drive from a cold start.
 

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There are a lot of different circuits on that link.
MOST involve a pot that you have to continually adjust and as such are for real hyper milers. I wouldn't recomend them, though it is the simplest one to build.

The one I built is set and forget. I love it. I'm in Canada, so obviously it's of more value to me here that it would be to you there. If your trips are med to long, I'd ignore it. If you do a lot of short trips though, it REALLY saves on gas, even in summer.

While I imagine any of these would in fact void your waranty, most can be removed in about a minute leaving no modifications to the original layout of the car. (ie no cut wires)

I think there is a guy on that thread "DAN" who actually built extras and is willing to sell them.
 
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