How to improve my MPG - Please help!

  #1  
Old 12-05-2008, 09:40 AM
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Default How to improve my MPG - Please help!

Hello everyone, I am new to this forum, actually just discovered it while doing a search on google. I recently bought a 2009 THH, and have driven about 1300 miles so far. However, I am disappointed with MPG. From what I had read and researched for the past 9 months, almost every article/website said 26 City and 27 Highway. Well, so far I am averaging about 23-24 MPG combined. I try to be very cautious with the way I drive (donít accelerate too quickly, let go of the pedal on down hill slopes, etc.). But it hasnít really helped much. I live in Connecticut and it is starting to get little colder these days. My driving conditions are, some of the driving has been in bumper to bumper and some just smooth sailing on the highway.

What can I do to increase the MPG, or what am I not doing. Please help!

Thank you.
 
  #2  
Old 12-05-2008, 10:09 AM
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Default Re: How to improve my MPG - Please help!

The HH power train is virtually a clone of that in the RX400h series, designed for stellar performance, quick 0-60 times, NOT FE. And then to boot the HH with a third row is a much heavier than the RXh.

The 2010 RXh is getting the V6 engine revised to the Atkinson cycle so there may be improved FE on the way, especially if the GS's V6 DFI technique is also used and used properly. But I suspect the Lexus engineers will still be oriented toward 0-60 times so I'm not encouraged.

If you don't do a lot of stop and go driving then you bought the wrong vehicle.


And remember the real gain for these HSD system is in city stop and go driving when you get FREE fuel via regenerative braking, and even then only in comparison to non-hybrid vehicles.

On the highway, cruising, there will be little or even no opportunity for energy recovery and yet the hybrid battery must still be used in conjunction with the ICE for proper e/CVT operation. So the hybrid battery will often need to be recharged via the ICE. Not only not for free, but a pretty lossy path in comparison to non-hybrid without this handicap.

On the highway the new I4 Highlander would undoubtedly yeild better FE than your HH.

All that being said...

Go to the dealer and have the c-best options set that allow you to disable the A/C functionality, normal and in defrost/defog/demist and leave them disabled throughout the winter months. Those go back to '01 and now there may be other c-best options now available. The ability to prevent the system from automatically switching into cooling mode, on the coldest darkest night of winter, wherein the windshield interior surface gets no warming airflow. When in heating mode, footwell outlet airflow, a portion of airflow is diverted to the windshield.

And rather than use an engine block heater as many suggest, and maybe compromise the longivity of the catalyst, I would use a ~500 watt ceramic heater w/blower on a timer to preheat the cabin before starting out in the morning. If you opted for the leather seating option and therefore heated seats I would splice in a 12 volt power suppy and pre-heat the seats via the same timer.
 
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Old 12-06-2008, 06:26 AM
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Default Re: How to improve my MPG - Please help!

First off, CONGRATULATIONS on getting a great vehicle. While the mileage is low right now it will get better. The Synergy drive takes about 8K miles to get broke in. As you have been seeing cold weather and your length of trips has it's effect on mileage. Short trips in cold weather will drive you mileage down as ICE runs till all the sensors are up to temperature. Longer trips where you can keep the engine warm, not many hills and not run at highway speed produces the best mileage. It's not uncommon for me to get 30+ on the back roads in the summer. Winter expect 20 - 24MPG, still better then the regular V6's 16-19 MPG in this weather.

Enjoy the new ride and keep up the saving tecchniques as it will pay off as it breaks in.
 
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Old 12-06-2008, 09:14 AM
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Default Re: How to improve my MPG - Please help!

Originally Posted by wwest View Post
The HH power train is virtually a clone of that in the RX400h series, designed for stellar performance, quick 0-60 times, NOT FE. And then to boot the HH with a third row is a much heavier than the RXh.....
The Lexus RX400H is the older smaller body style which accounts for most of the weight difference. The second gen Highlander is larger and heavier. The third row seats can come in handy in a pinch if you must drive around lots of kids occasionally and the ability to transport 7 people makes the vehicle more efficient for its intended purpose and size.

Originally Posted by wwest View Post
If you don't do a lot of stop and go driving then you bought the wrong vehicle.

And remember the real gain for these HSD system is in city stop and go driving when you get FREE fuel via regenerative braking, and even then only in comparison to non-hybrid vehicles....
In my experience, I don't find this to be accurate. I get my best mileage driving between 35 and 40 mph continuously without stop and go. While regenerative braking does recycle otherwise lost energy, the HSD system provides greater mileage gains by shutting down the engine and allowing the vehicle to coast or run on battery while driving below 40 mph.

I also find that driving at an uninterrupted 40 to 45 MPH gives me much less MPG than below 40 MPH since the engine must now run continuously and not shut off at these speeds while the engine is in one of its least efficient ranges (low rpm, low load, low vehicle speed).

Originally Posted by wwest View Post
On the highway, cruising, there will be little or even no opportunity for energy recovery and yet the hybrid battery must still be used in conjunction with the ICE for proper e/CVT operation. So the hybrid battery will often need to be recharged via the ICE. Not only not for free, but a pretty lossy path in comparison to non-hybrid without this handicap.....
While driving at highway speeds (50+ MPH), there are small added losses in converting mechanical power to electrical power in the generator (M1) and then immediately feeding that electrical power into the motor (M2) where it is reconverted into mechanical power. The hybrid battery is bypassed for most of the power flow under this operating mode so the less efficient electrochemical conversion losses are minimized.

However, the efficiency advantage of the hybrid drive at highway speeds is its continuously variable transmission. The engine is by far the most inefficient link in the entire drive train wasting about 70 percent of the fuel it uses. Allowing the engine to continuously operate at its most efficient speed and load more with the continuously variable HSD transmission more than makes up for the small efficiency losses in the mechanical -> electrical -> mechanical power conversion.

Note that the hybrid version of the Highlander has a better highway fuel efficiency rating than the otherwise equivalent non-Hybrid Highlander.
 
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Old 12-06-2008, 10:54 PM
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Default Re: How to improve my MPG - Please help!

Originally Posted by Don R View Post
The Lexus RX400H is the older smaller body style which accounts for most of the weight difference. The second gen Highlander is larger and heavier. The third row seats can come in handy in a pinch if you must drive around lots of kids occasionally and the ability to transport 7 people makes the vehicle more efficient for its intended purpose and size.



In my experience, I don't find this to be accurate. I get my best mileage driving between 35 and 40 mph continuously without stop and go. While regenerative braking does recycle otherwise lost energy, the HSD system provides greater mileage gains by shutting down the engine and allowing the vehicle to coast or run on battery while driving below 40 mph.

I also find that driving at an uninterrupted 40 to 45 MPH gives me much less MPG than below 40 MPH since the engine must now run continuously and not shut off at these speeds while the engine is in one of its least efficient ranges (low rpm, low load, low vehicle speed).



While driving at highway speeds (50+ MPH), there are small added losses in converting mechanical power to electrical power in the generator (M1) and then immediately feeding that electrical power into the motor (M2) where it is reconverted into mechanical power. The hybrid battery is bypassed for most of the power flow under this operating mode so the less efficient electrochemical conversion losses are minimized.

However, the efficiency advantage of the hybrid drive at highway speeds is its continuously variable transmission. The engine is by far the most inefficient link in the entire drive train wasting about 70 percent of the fuel it uses. Allowing the engine to continuously operate at its most efficient speed and load more with the continuously variable HSD transmission more than makes up for the small efficiency losses in the mechanical -> electrical -> mechanical power conversion.

Note that the hybrid version of the Highlander has a better highway fuel efficiency rating than the otherwise equivalent non-Hybrid Highlander.
Since the HSD V6 in the HH is quite seriously derated the closest eqivalent might be the new Highlander 4 cylinder and I would bet that the 4 cylinder will get at least 10% better hwy FE than the HSD version.

Or someone could derate (restrict the throttle opening) the V6 in a standard Highlander and still get better FE than the HSD version.
 
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Old 12-08-2008, 08:14 AM
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Default Re: How to improve my MPG - Please help!

We drive most of the time with "econ" on and that makes a difference. Use the MPG chart on the display as a guide to your driving habits. Starting out slowing from a stop seems to really help. We get as much as 32 MPG on trips and 25 mpg around town.
 
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Old 12-08-2008, 09:03 AM
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Default Re: How to improve my MPG - Please help!

Bob, Thank you.

I will definitely try some of the techniques you all have mentioned and see if it improves the MPG. I guess I will also wait and see how the MPG improves as I break in the car a little more. Maybe since this is our first hybrid vehicle, we just need to understand the vehicle a little more.

Thanks a bunch.
 
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Old 12-12-2008, 12:47 PM
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Default Re: How to improve my MPG - Please help!

Razz.

My observations having had my HH for 18 months... MPG figures vary considerably with style of driving, terrain, type of journey, it's very difficult to absolutely compare with others. Just try resetting the Avg MPG (that's in the 06) and experiment and you will see what I mean. It would be good to then compare those experiments with a regular Highlander, my business partner has one - we are getting about a 3:2 ratio - she puts in 3 gals I put in 2, that works for me.

There are folks who get fantastic MPG, they pump up the tires to reduce rolling resistance and other tricks - great. To be honest, if we are really focussed on reducing our consumption we should all be driving a Prius (in this forum) and working from home as our SUV is never going to be a particularly fuel efficient vehicle unless compared solely against others in the SUV class. Of course perhaps I shouldn't even be here as I quite like the V8 performance occasionally but feel good because it doesn't mean I do 12 mpg.

Don makes a good comment about driving within the speed parameters where the engine shuts down (<40mph), of course that assumes you are in a situation where you can choose your own speed, not always the case as we have to work with the traffic around us.

You are right with your last statement - just need to understand the vehicle a little more - congratulations on your purchase - we absolutely love ours.
 
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Old 12-15-2008, 02:59 PM
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Default Re: How to improve my MPG - Please help!

No vehicle gets peak FE out of the box hybrid or not, and 1300 is barely past initial break in. Add to that a 10-15% deterioration for any vehicle in winter driving due to cold temps and winter gas formulations (depending on what they do in your area) so you sound to be doing fine.
 
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Old 12-17-2008, 09:04 AM
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Default Re: How to improve my MPG - Please help!

Just an update from this past weekends driving.

My wife and I drove the THH quite a bit this past weekend, and I used some of the techniques others have mentioned and tried some of my own. By just doing some basic and above mentioned techniques, I was able to improve the MPG by about 1 Ė though not much, but I guess still an improvement and encouraging. Hopefully I can hit the 25/26+ threshold with more practice, understanding of the weaknesses and strengths and warmer months. By the way, we really love this vehicle.
 

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