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Discussion Starter #1
I drive over two mountains, one right after the other, on my way to work, and my mileage drops considerably. If I'm averaging 68MPG, by the time I get to the top of the second mountain, I'll be around58MPG. This is with around 20 to 25 miles on the trip. Today I was at 84MPG and 19 miles, and got trapped behind a tractor trailer, which killed me. At the top of the hill I was at 64MPG! I've tried flooring it, getting a "running" start, going around 50MPH, and it doesn't help. Flooring it actually seems to work the best. Anyone have any suggestions on the best way to go up a hill and not lose to much mileage, or is it hopeless?
 

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The effectiveness of the Insight's best fuel miser features depend much upon what you mean by "mountain" and other driving conditions. I live among the Blue Ridge Mountains in Virginia. People near the Rockies think it is silly to call these "mountains". Never mind that Apalachia has the oldest mountains in the world and the second most complex geology in the world (next lower in complexity to the Swiss Alps). Younger mountain ranges are taller, having not yet been eroded.

The Insight's battery capacity seems to be almost perfectly tuned to these mountains, running the batteries through nearly a full cycle climbing up and riding down at highway speeds (around 70mph). I've driven in North Carolina on some slightly taller mountains trying to maintain that same speed and the batteries ran out. The downshift arrow lit up and gas mileage plummetted as I had to rev up in 3rd gear to make it to the top.

I suspect if I'd been satisfied to drive more slowly, I could have gotten farther before that happened. I wasn't willing to do that, however, and was satisfied with the compromise between performance and gas mileage.

Anyway, reading the numbers you quote, I think you might be expecting a little much of the Insight. You'd be challenged to get HALF that gas mileage on those hills in any other vehicle with four wheels, or even two wheels, for that matter. Most cars wouldn't get a quarter that gas mileage.

Fuel is burned to do work. Hills are more work than flat land. Gas mileage will be worse on hills than on flat land.

The Insight helps quite a bit to use the downhill energy to power the uphill energy, but when you start worrying about the top end of your gas mileage (over 60mpg) you have to realize that you get better gas mileage if you neither charge nor discharge the batteries, since no energy system is perfectly efficient and when you transfer mechanical energy to electricity, some energy is lost. When you store the electricity, some energy is lost. When you transfer the stored electricity back to mechanical energy, some energy is lost.

This is exacerbated if battery temperatures run cold. Coldness inhibits battery chemistry, so you'll get better gas mileage in summer than winter, unless you have extreme heat. The electronics try to protect the batteries from chemical and physical damage from extreme heat by basically shutting down the electric side of things until the batteries cool down.

All this is to say, the engineers at Honda have done a remarkable job of working every compromise they can to give you the best gas mileage and lowest pollution that anybody can produce in a car. You can help with gentle driving habits, minimizing both the boost and charging of the batteries, but you have your own compromises to make, like driving safely in traffic which doesn't give a damn about your gas mileage.

Celebrate the good gas mileage you are already getting. Can you imagine anyone in any other vehicle complaining because their gas mileage dips into the low 60s?

Thou dost protest too much.

While I commonly got over 70mpg in summer, mostly on what was a half-hour commute, mostly on Interstate highway, during winter, it dropped to around 60mpg for the same commute. I got married and moved into town and drove mostly in town on short trips where gas mileage fell to the lower 50s in warmer weather and often down into the 40s in winter. In the 45,000 miles I drove the car (before it was recently destroyed in an accident, or rather AFTER the accident by zealous rescue workers and the Jaws of Life) the lifetime average was 57.something mpg.

On this list, this is no great achievement, but the simple truth is, if I drove those same miles that same way in any other car, I'd be getting closer to 20mpg. I feel okay about myself and the Insight for scoring so close to 60mpg under those conditions.

Will M
 

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Will, trust me, I am very happy :D with the mileage I am getting. I was just wondering if there was some way to minamize the mileage loss from the hills. I'm not sure you would call them mountains or large hills. They are on route 7 in Va just outside Berryville. I've been to Colorado and they are nothing like what is out there, and I'm oringinally from Pennsylvania(Altoona), and we have some "mountains" around that area too. By the time I get to work I'm usually back up around 70 to 73MPG, but natually I'd like to get as high as I can. I make short trips (5 to 10 miles) around town and usually don't get less than around 65MPG. I've gotten as high as 91MPG. A few stop signs and one or two lights..............Bill Z
 

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Just another note about efficiency:

When I lived in a solar electric house, the electrical equivalent of a car's gas guage had to be manually configured for battery efficiency. Apparently, it is impossible to actually measure amps directly. Instead, you put a low-resistance resistor in the line and measure the very slight voltage drop across that resistor and calculate what the amperage must be to cause that voltage drop. Measuring amp-hours is another layer of abstraction added to that.

The amp-hour guage that was supposed to predict when my solar electric system was fully charged or about to black out had to measure amp hours charging into the batteries or discharging from them, and when I told it my interpretation of what the battery efficiency was, it could then figure out its guess as to the battery's State Of Charge. This is basically a very scientifically derived wild guess.

I had to experiment to get this number right, noting when the batteries were bubbling (fully charged) whether the meter said they were fully charged or not and resetting the top-of-charge point on the meter and adjusting the efficiency setting to make the guess work better next time. My lead-acid batteries were about 90% efficient. In other words, if I put 10 amp hours of electricity into the batteries, I could get 9 amp hours back. The other amp hour was consumed by resistance in the wiring, heat conditions affecting battery chemistry, the inherant inefficiency of electric/chemical conversion, and elves, dragons and other mysteries.

Lead-Acid batteries are the most efficient batteries man can make. Cars, laptops and hand-held vaccuum cleaners would all use lead-acid batteries, except for one thing: They are heavy, so they are not all that good for devices you wish to carry or otherwise transport.

Ni-cads, Nickel-Metal Hydride and Lithium batteries are much lighter than lead-acid for the charge they can take, so they are preferred for portable settings. Ni-cads have really bad "chemical memories" meaning that unless you very loyally manage their state of charge, discharging them all the way to zero and then charging them all the way to the top, and don't let them sit at one charge level for too many days, the battery chemistry changes and the batteries stop working. The top and bottom of the charge get closer and closer to each other until there is no longer any way to store electricity in these batteries or get electricity out of them.

Lead-acid batteries can get a form of chemical memory at the bottom of their charge, but not the top. Sulfur from the sulfuric acid deposits itself on the lead plates as the battery is dischargeed, leaving water where there was sulfuric acid and sulfur deposits where there were clean lead plates. When you recharge a lead-acid battery, the sulfur dissolves back into the water, turning it back into sulfuric acid.

If you let a lead-acid battery sit too long at the bottom of its charge, the sulfur deposit hardens and will be quite resistant to dissolving back into the water. Overcharging lead-acid batteries can help because it causes the plates to heat up enough to boil water. The boiling action physically breaks the sulfur deposit and pushes it off the plates. Some of this sulfur will now dissolve into the water, while the rest drops into the dregs at the bottom of the battery.

Lead-acid batteries generally die because of one of three causes:

1. The plates heat up so much that they warp far enough that the positive and negative plates touch, shorting out the battery, killing all electricity in the cell. This is a classic "dead cell" in a car battery, for example. Car batteries are vulnerable to this because the lead plates are very thin, giving you maximum surface area in order to pull a lot of amps quickly to the task of starting an engine in cold weather.

Deep-cycle batteries used in solar homes or fork lifts or floor scrubbers use much thicker plates that are resistant to warping. They are often intentionally curved plates, specifically shaped to resist warping.

2. Some of the sulfur pieces bubbled off the plates fall and do not dissolve, settling into the bottom of the battery. They combine with other conductive contaminants in the dregs at the bottom of the battery until the deposit becomes deep enough to touch the bottoms of the plates and short them out. This is the OTHER way to get a dead cell.

3. Batteries can also die because they run dry. If you let them boil off their water until the lead plates are exposed, the deposits on the plates harden so much as to ruin the battery.

The chemistry is different for other batteries, but all of them have some form of chemical memory. The nickel-metal-hydride batteries chosen for the Insight are very light for the charge that they hold and very resistant to forming chemical memory. This is enhanced by the electronics in the car which will periodically discharge and recharge the batteries for the specific purpose of defeating any chemical memory that would otherwise form. This makes the batteries last a long time. That's why they offer a warranty for 8 years or 80,000 miles.

Still, I strongly suspect that these batteries offer less than 90% efficiency, even in good weather. If you really want to get the absolute best gas mileage you can, then try to not drive the Insight so that the boost light comes on.

Meanwhile, remember that the electric side of the Insight is not really there in order to give you the absolute best gas mileage possible. If all you care about is gas mileage, remove the battery and drive the gas engine only.

The electrical side is there because that 1-liter, 3 cylinder engine that gets GREAT gas mileage is extremely unfun to drive. Low end torque is disgraceful. Accelleration is laughable. Every time you pull out into an entrance ramp, you'd be chanting, "Come on, little Insight. You can do it. Come on...." and you'd have a lot of time to chant, since the 0 to 60mph time would be measured in minutes instead of seconds. You'd have to take every hill in 3rd gear. Forget passing anyone under any conditions.

The electric side gives you all the surge that the gas engine lacks. Every time you use the electric side, you lose gas mileage. Meanwhile, you don't lose MUCH gas mileage, and you gain a very fun ride. You get the accelleration that would be impossible for a gas engine that can yield anywhere near this gas mileage.

That's why it is a hybrid. Life is a balance. Balance your driving by enjoying the spunkiness of the electric boost every now and then, and the rest of the time, you sip very little gas cruising at extremely high efficiency.

Sorry for babbling. I like this stuff. It's fun to think about.
 

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I usually approach hills at my usual lean-burn pace. On small hills or slope changes I use the assist when my speed drops below 50-55 mph, but I don't floor it all the way, maybe enough to get 3/4 ASSIST lit up. This keeps my MPG at 40-50 mpg. If that's not enough to maintain speed, I floor it.

If I know I can't make it over without flooring it (on hills I am familiar with) I floor it right when I hit the grade rather than waiting for the car to be slowed.

The justification for flooring it and burning that gas is to discharge the battery as much as possible. The idea being that when you go back down the hill, you can leave it in gear, take your foot off the gas and start regen. That's the only suggestion I can make to you -- try not to burn any gas on the way down. I do a lot better this way than by putting it in neutral and coasting down the hill.

I've tried something like this on a very steep hill along the 101 freeway in California between Thousand Oaks and Camarillo, recording my mileage up and down the same stretch of hill using the segment display. I have never gotten over 70mpg for the combined "trip." It sounds like you're doing pretty well.
 

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thank you Will. That was a very informative discourse on battery technology, amps, and such.

__________Ron Wolf
 

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I am going to try the Grapevine tonight going into LA out of the Valley. Wish me luck!!!
 

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Just a few weeks after getting my Insight I hit the Grapevine (Going north, took 101 South) I was probably going a little too fast at times up hill and with only a few hundred feet to go I lost my assist. The battery had dropped to 1 bar, so I had to put it in 3rd and lived with 35-40mph for the last few minutes.

Downhill made up for it though, charged the battery to about 80%+. I will have to make the trip again some time to see if I can do better on that grade.
 

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I have found that using the mpg formula stated at http://www.insightcentral.net/forum/viewtopic.php?t=34
has helped me understand why my mpg is what it is. It is stated here again for convenience:

MPG = 2*(mpg1*mpg2)/(mpg1 + mpg2)

where MPG is the total mpg over a distance D, and mpg1 & mpg2 are the mileage along the first and second halves of D. So this formula applies only when mpg is taken over two equal distances. And the maximum MPG possible is 2x the lower of the two mpg's.

Like many people who commute, I take the same road to and from work (namely the I-5 from La Jolla to Carlsbad for those in SoCal area). So that means that climbing any inclines on the way to work is matched (in distance) with descending those inclines on the way home, and vice versa. Since my commute is mainly "hilly", the overall mpg is pretty much limited by the mpg it takes to go up vs. down.

Up until a month ago, it took me 50mpg to go up hill with assist, and say ~100 to go down comfortably. This came out to be ~66 mpg according to the formula. I was actually getting between 60 and 65 mpg per tank of gas.

A few weeks ago, I discovered that I could get 55mpg going uphill and still have assist come on. The formula now predicts ~71 mpg, assuming 100mpg going down. And on the last tank of gas, I was getting about 69.5 mpg, and currently I am getting 73mpg over 200 miles.

Of course there are many other factors not taken into account, such as tire pressure, weather, mileage outside of commute, and the occassional need-for-speed urges, etc. Well, anyone in SoCal this past winter will confirm that it was a warm winter, and although quite a bit of rain, still not enough to dispel Sunny SoCal weather. And my commute (50mi/day) makes up the majority of miles/tank. I keep my tires inflated to ~44psi every week. So overall, there seems to be ~5mpg increase since I switched from 50mpg to 55mpg going up inclines on the commute.
 

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On my trip to LA over the Grapevine I made it over doing 65 MPH and used 1/2 of my battery power. It completely recharged before I was through Valencia. Same thing coming home. I went from Fresno to Anahiem, drove around Anahiem and back over the Grapevine to the base on the Northern side and only needed 8.5 gallons. Over 460 miles and almost 55 MPG with a CVT. I was very proud.
 

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I have driven over both the Appalachians (interstate 70) and the Rockies (U.S. 40). Here's the best methodology for me:

-UPHILL: Shift down to 3rd.

-DOWNHILL: Shift up to 5th... use regenerative braking.

Sometimes depending on terrain, I just stay in 3rd the whole time without shifting. I've found that it's best not to drain the battery.
 

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Commutes are a great way to improve driving techique for best gas mileage. When I lived in New Jersey I drove a 145 mile round trip daily. When I had enough practise with driving technique I logged my highest MPG on one trip at 77 and another at 74. That said, my typical driving style would yield about 60 mpg.

Whether hilly of flat, any trip may be an altitude change up in one direction and down in the opposite, cancelling out the grade.

When I drove cross-country in my Insight I was crusing at a fast pace. I had my wife and our luggage with us. Although we drove it hard the whole way I was impressed that I had over 50 mpg average for the entire trip.

Driving in the foothills of the Sierras the battery seems woefully small. When going uphill for well over 5 miles the battery peters out and I had to down shift to maintain speed. When going down steep hills for miles, I'd downshift so that the regen and engine drag would let me coast without hitting the breaks.

I don't think it helps much to look at efficiency for small segments. At least in my driving I've found that it takes a driving style to achieve the best efficiency, a far greater factor than tire inflation or anything else.
 

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Insight Driver said:
... I don't think it helps much to look at efficiency for small segments. At least in my driving I've found that it takes a driving style to achieve the best efficiency, a far greater factor than tire inflation or anything else.
The thing is, tire inflation and looking at efficiency for small segments is part of one's driving style. The same person who pays attention to tire inflation also pays attention to staying below the critical top speed for lean-burn, etc. The person who doesn't bother with tire inflation doesn't bother with driving gently and doesn't watch and learn from the continuous mpg meter.

High mpg is achieved by juggling a matrix of factors. Buying an Insight instead of a Ford Explorer is a big step. Driving gently is a smaller, but significant step. Tire inflation is a factor that requires less persistant attention, but improves mpg with whatever other techniques you use.

It's the sum of many factors.
 

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I completely agree that achieving best mileage is a sum of many factors.

I have had some benefit of driving in different conditions. I used to drive on a mostly-interstate 145 round trip commute daily. I now drive a 16 mile city, stop and go round trip daily.

When I got new tires (same make as OEM) I noticed less than a one mile per gallon change in weekly efficiency. Overinflating my tires by 5 pounds yeilded me less than a one mile pre gallon change in weekly efficiency.

When I drove like typical commuters my mileage would drop by 10 miles per gallon efficiency change. In my 16 mile round trip traffic makes a big difference in how many cycles I wait for a light change and what percentage of time I sit at idle. I have found, driving for economy there is a 5 mile per gallon difference in efficiency per week if I change my commute time by one hour earlier or later.

One thing I do enjoy very much about the Insight is that it has made me aware of driving style being such a big factor in economy.It's sad to see those SUV drivers gunning it from one light just to sit at idle a few seconds longer at the next light. I accelerate slowly and decellerate for maximum regen before I must put my breaks on.
 
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