Does Toyota, the people who designed the Highlander Hybrid, or others offer tips on reasonable, safe, and legal methods to improve the gas mileage in Highlander Hybrids, methods that also do not void the warranty (or extended warranty)?

What I have: 2006 Toyota Highlander Hybrid with front wheel drive (no EV mode to my knowledge); I purchased and plugged in a Scangauge II for additional information last year. I also realize there are many articles on improving driving habits to improve gas mileage, many of which I am doing and work quite well. Are there any tips that might apply to Highlander Hybrids or similar vehicles that may not apply to other vehicles?

What else may I do? Are there any after market modifications that may help, for example a higher flow exhaust system? I have not found any catback systems for Highlanders. Would any catback system work or could this make the MPG worse? While I already have a K&N "oiled" cotton filter, I purchased this as I like to clean the air filter every other oil change. I may switch to synthetic oil during the next oil change (ex. maybe 0-30W or 5-30W).

I am looking for what I consider "reasonable" methods and tips. I am aware of "hypermilers techniques to overinflate tires (sorry, I keep my tires consistently inflated to what is listed on the door ), consideration to closely tailgate large trucks (I prefer to see the side mirrors on large trucks so the driver can SEE my vehicle). I do drive slower, when possible. MPG is more important than average speed.

A little knowledge about how the propulsion systems works in Highlander Hybrids work may also be useful (ex. what could be the ideal throttle position setting and ideal engine RPMs for acclerating under various conditions).

Yes, riding my bicycle or walking yields the best MPG with no modifications.

 

Prevent the A/C compressor from operating EXCEPT to initially cool the cabin down to your comfort level or if the OAT is so high, or sun so bright, that it is needed for cooling full time. When using the A/C for cooling ALWAYS have the system in recirculate mode.

But ALWAYS keep it in fresh mode whenever heating is needed, you have the manual flow valve (below) open.

Even when you need full time cooling you can purchase and install a manual water flow control valve at Home Depot to shut off the HOT coolant flow to the heater core and thereby bypass/disable the reheat/remix mode of your climate control system.

Bypassing the reheat/remix mode will substantially reduce the A/C compressor cycling periods.

I have always unplugged my A/C compressor clutch during the winter months up until Lexus provided a means for doing that via two c-best customization options.

 

These are excellent ideals which I had not thought of (especially the flow valve which I will install

I am also considering replacing the stock muffler with a Flowmaster series 50 or 70 "higher flow" muffler, removing the unneeded twists in the exhaust pipe, after the first muffler, and removing the second, smaller flow through muffler (located under the rear bumper). This second muffler is slightly visible from the rear of a Highlander.

For the twists in the exhaust pipe, I have front wheel drive only Highlander Hybrid. These twists are needed for the all wheel drive Highlanders, but not on the front wheel only models (there are no rear wheel drive components to get over). Toyota uses the same exhaust pipe, apparently for all Highlander versions. The exhaust pipe is also unusually crimped after the first muffler, narrowing its diameter. This *could* add backpressure, which reduces mileage. Dear Toyota, I paid thousands over the cost of a standard Highlander for improved gas mileage. I did not expect this in the exhaust system. I would had preferred to see a straight exhaust pipe, with one high flow muffler.

I have a Scangauge II; I will let others know my results. I am trying to determine if I should get a muffler with one exhaust outlet - the same as the stock muffler or two outlets - two pipes. If done incorrectly, I would slightly lower my mileage.

Despite all of the above, I still believe driving habits influence gas mileage more . . or walking . . or riding a bicycle . . or taking mass transit.

End

 

Here's a couple ideas I've picked up from several threads --

I'm guessing you might be in Minn? If so, you might benefit from adding an engine block heater. This preheats the engine, reducing the time the car runs in 'conventional' mode getting the engine warmed up. Especially for short commutes, like my wife's, I think this will be a big win. My Lexus parts guy quoted the part at a reasonable price, but said they couldn't comment on the labor, since they couldn't find the procedure in their books. My next step is to print out Fusco's detailed procedure for them to look at.

Once warmed up, use the engine to accelerate from lights, then when the terrain allows (motors have sufficient power to carry you) come completely off the accelerator to shut down the engine, then back on just enough to maintain your speed. Doing this diligently on surface routes can make a huge difference in mileage.

If the max pressure rating on the side of the tires is higher than that on the door sticker, consider bumping up the the tire max.

I bought one of the ScanGauge II's for my conventional Explorer. With the 'instant feedback' I'm getting now, I think I'm boosting my 16 1/2 MPG average over the last 70k miles up towards 20-ish. And with the 'trip gas consumed' I'm better able to weigh whether a slightly longer but higher MPG route is really a win. I haven't calibrated the SG's fuel flow measurements yet, but if those numbers are sustained, it'll have paid for itself in under five months, at $4/gal.

Benton 6jun08

 

I would forget about the exhaust mod/muffler. Intake and exhaust mods won't improve part throttle FE. The lower resistance air filter won't help part throttle FE. In a modern vehicle,any lowering of the resistance you make in front of the throttle valve the is balanced by the drive by wire "computer" closing the throttle valve a bit more so you get exactly the same fuel and air in at the same load and RPMs.

The exhaust is a slightly different situation, but the tiny difference in pumping between the OEM muffler and your aftermarket muffler(which might improve FE) will probably be negated by your muffler not being as well tuned as the OEM muffler.

Save your money; the OEMs do a very good job on part throttle FE-especially on a mpg type vehicle like the HH.

I would look for better-lower RR tires- but Toyota probably beat you to it. There might be better- lower RR tires - in the furure,so keep your eyes open.

You might consider weight loss. There are some very lightweight wheels out there. They would also give me pause because the QC won't be as good as the OEM QC.

I'm certainly negative today, but other than tires, tire pressure, syn oil, weight loss and extreme aero mods(very low front spoiler or an entire skirt coming very close to the pavement) it is tough to find mods that help FE. The engine block heater is a great one for colder climate folks,and pretty good for occasional cold weather folks.
Charlie

 

I agree that any intake or exhaust flow modifications would be virtually useless for a vehicle with a high FE target rather than a HP/Torque target. Most vehicles today cruise along with the engine at about 2200 RPM and thus the throttle plate itself becomes the major onstruction/retriction to intake airflow.

Obviously the OEM exhaust system, designed to provide reasonably free flow at 5000 RPM and under a heavy engine loading, will provide more than adequate flow capability at 2200 RPM.

The EBH, Engine Block Heater, might just turn out to be a mistake in teh long term, possibly a BIG mistake. In order to more quickly "lite-off" the catalytic converter the engine and transaxle control "mapping" is modified until the engine reaches normal operating temperature.

An EBH might easily shorten the time the engine takes to climb to that normal operating temperature, leaving the catalyst at a substandard temperature, thereby shortening the life of the catalyst.

Seat heaters, to me, seem to be an extraordinary "waste" of energy for any hybrid vehicle. Were I to buy a hybrid I think I might "go" for cloth seats.

On the other hand that might be a good place to use an EBH-like device. Preheat the leather seats (and the entire passenger cabin..??) with grid power.

 

I seem to be crossing paths a lot with you today, wwest. You see to both know a lot, and forget the basics...

To initially cool down the cabin, you want to NOT use the A/C compressor until the inside is similar to outside air. If the outside air is cooler that what's in the cabin, take advantage of that without engaging the rather costly A/C. Even better, roll down the windows for a few minutes to quickly vent the hot air and cool the interior. Even at highway speeds, where extra drag is worse that A/C usage, the benefit of quickly performing this act would offset the long time that A/C would need to cool.
If, for some reason, you can't open your windows AND you can't wait for the vents to cool the cab down to ambiant, whatever you do...DON'T use the recirulate mode. If the air is cooler outside (and that is what we are describing) you want to draw that already cooler air in the A/C rather that try to cool down air that is considerably hotter. Once the inside get below/equal outside temp, then by all mean turn on the recirulate mode....unless its raining, in which case you will probably fog up your windows very quickly.

 

No, in this circumstance the dewpoint is not likely to be in the range conducive to fogging up the inside of the windshield.

Absent the rain, just high humidity, the outside, maybe.

 

Sorry wwest, I definatly seem to be missing some points today.

I'll have to re-read, but what you are saying in this message sound completely correct. And I too hate the automatic switch....while I don't mind the system being automatic...it needs to be smarter about the whole process. Someone has even suggested getting rid of the traditional A/C for the cab, and instead using either seats that can be heated/cooled and/or using vents located where it can put air directly on your head. Frankly I have seen these techs and I'm physcially not comfortable with them, but I suspect I could get used to it after a few days.

 

The are two major "contributions" with respect to heating/cooling, for human comfort.

The temperature of the air surrounding us is often only half of the human comfort equation.

The second half is the radiant heating or cooling effects.

In the wintertime we are much more comfortable with the surfaces/objects surrounding us warmed to a great enough degree that the radiant heat from them helps to keep our human body warm and comfortable.