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Discussion Starter #1
a post to boast my just completed 44.4 mile round trip commute with a fabulous 80.2 MPG. I was going 42 mph in places where most drivers do 85, but also 62mph in some places as well. This trip included haveing the windows down much of the southbound direction due to the first elevated temperature day of the summer. southbound at 2p.m., northbound at midnight.

brft drvr
'03 silver MT no A/C
 

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I once got over 90mpg on a 60 mile round trip, but that was before I knew about this group and I didn't make an effort to record the exact number. I know it was more than 90 and less than 91, and the trip was more than 60 miles and less than 70. That much I remember.

I was trying to figure out why it was so much better than my average driving. My only clue was that the SOC was extremely low, while my normal driving kept it at top charge pretty much all the time. I figured that likely the control system decided that it was time to cycle the battery, so I got more boost than I needed, hence the amazing gas mileage. The next trip, gas mileage was lower than normal, likely from recharging the battery.
 

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kudos, rodneyAB.

I've sometimes wondered if my MT would do better with A/C on and windows up or A/C off and windows down. I usually opt for A/C on.
 

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AC

The AC will take a bigger cut out of your efficiency than having the windows down. And in regard to the SOC effects on fuel efficiency I believe it has a minimal effect.
Consider that all the energy that moves your car comes from the engine (The battery gets charged by the engine). If we had two identical cars driving under the same conditions but one had a more aggressive battery assist I would expect the less aggressive battery to get better mpg. This is because the conversion of energy between the gas engine and the battery is not 100% efficient so the more you cycle the battery in normal driving the more energy that is lost to heat. But wait wouldn't that mean a hybrid is less efficient than the gas only version which is not true.
The benefit the battery provides is as a buffer to allow your engine to operate in its most efficient range. Ofcourse we use a smaller engine also. The key to high mpg has to do with keeping the engine in lean burn as much of the time as possible. The battery also allows us to use a higher gear than other vehicles. When I am crusing down the road I can easily climb a steep hill in 5th gear and maintain speed thanks to the electric assist. In contrast my Civic VX which also has a Vtec-E engine can't maintain the speed in 5th gear on the same hill without downshifting (even though it has a 92HP 1.5 L version of the Vtec-E). Thus with the IMA as a power buffer I can keep the engine at a more efficient operating range.
For the above reason I also disagree with the 1-2-5 shift pattern. Fast acceleration will always require more energy than a slower start. As a result yes you get the battery assist but that battery will have to be charged by the engine eventually (unless you live in a area that has only downhill sections of the road to charge the battery). Have fun, Rick
 

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Re: AC

Rick Reece said:
..And in regard to the SOC effects on fuel efficiency I believe it has a minimal effect.
Consider that all the energy that moves your car comes from the engine (The battery gets charged by the engine). If we had two identical cars driving under the same conditions but one had a more aggressive battery assist I would expect the less aggressive battery to get better mpg.
You missed my point. Yes, all the energy comes from gasoline and there is efficiency loss when combustion is converted to kenetic energy, then converted into electricity, then chemestry, then back to electricity, then back to kenetic energy.

The point is that if you start checking mpg on a system with a fully charged battery, and finish checking mpg on a system with a fully depleted battery, you get artificially high mpg readings because you've consumed energy stored from gasoline burned before you ever started checking mpg.

Later on, your net mpg will likely be worse once you get the battery back up to fully charged, but for the short duration of the test, starting with high SOC and ending with low SOC, mpg looks good. That's why checking mpg on distances less than a full tank of gas is not really meaningful unless you compare starting and ending SOC.
 

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Re: AC

Rick Reece said:
Fast acceleration will always require more energy than a slower start. As a result yes you get the battery assist but that battery will have to be charged by the engine eventually
Slow acceleration: The engine gets you up to speed slowly, burning gasoline because it is not operating in its most efficient state, which is a lean-burn cruising speed. You spend more time burning gas inefficiently.

Fast acceleration: The battery gets you up to speed rapidly. This maximizes the time you are in lean-burn mode and driving most efficiently. You have lost charge, but you then charge the battery when you slow down, or while you're cruising.

In effect, the fast acceleration charges the battery during a cruise or with regen-braking, while slow acceleration "charges" it (relative to the fast case, by not using it) under acceleration. It is more efficient to charge the battery in the former case rather than the latter.
 
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Discussion Starter #7
mpg over short distances

81mpg over same 44 mile commute. I have not been checking MPG over a Tank's distance, better look into that. The high MPG over a short distance is meaningful to me in that it is instant feedback to driving technique over a repeated short distance. I have not been depleting the battery, generally just a few bar difference at any given time, mostly three quarters or greater full. I tend to accelerate slowly whenever possible, and find a slow accelration from a stop light "preserves" the higher MPG, whereas fast acceleration will plummet the display. just checked the LMPG at 69 over 5100 miles. so thats taking into account all the around town driving and fast accelerations I've done. 69mpg is a bit dissapointing, but more meaningful, than my "star" for the day 81.

brft drvr
'03 MT no A/C
 

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69mpg should not be disappointing. It's higher than the EPA figures, which for most cars is purely theoretical, since it is done on a treadmill without wind resistance, traffic or other real-world factors. They simulate traffic, etc. but the point of the EPA figures is consistency between vehicles, not accuracy to the real world.

Unfortunately, even this consistency is false, since a brick-shaped SUV with parachute-like fake scoops all over it is not penalized for bad aerodynamics, and the Insight is not credited with good aerodynamics.
 

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Hi Insight friends. I just joined this group after owning the car for allmost two years. We bought it used with 4488miles on it, it now has 46858. We love it. The car is capable of incrediable performance, and with a lot of practice, the team of car and driver can achieve amazing results. I see that rodney is boasting about his personal best, and I would like to do the same. I just got 91.1 MPG on the last tank of gas. I went 876.4 miles over the last month mostly back and forth to work and one trip from Tucson to Phoenix. I have owned a lot of other high mpg cars( Isetta, Messerschmitt, Subaru 360, Subaru Justy, Sprint, Geo Metro etc.) and they all could get good mpg if you were very careful, but the Insight gets great mpg normally and amazing mpg if you are very careful.
 

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Tim,
I don't think a short burst of acceleration in 1st/2nd gear at WOT with battery assist will be as efficient as a more modest approach using all five gears. It would be hard to test and would probably vary depending on the driving after the acceleration. I suppose the most advantages location for your approach would be entering the freeway so that you would have a steady cruise to get the battery charged (If you are using the brakes then you will need another WOT to speed back up). I plan on doing some testing in July so perhaps I will get a good comparison of this issue. Have fun, Rick

SNO,
Just to give you something to shoot for my best tank 104.3 covering 1102.1 miles. The best part was that it only took 10.412 gallons to fill up. A steady cruising speed on the Interstate in the summer can produce incredable numbers.

Will,
Sorry about the miss read. I see what you mean now. Have fun
 

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Rick Reece said:
I suppose the most advantages location for your approach would be entering the freeway so that you would have a steady cruise to get the battery charged...
Yes, I think you're right about that. When I'm doing city driving, or if I am in stop and go freeway traffic, I am much more casual about accelerating, plus I rarely enter 5th gear.
 

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Rick
I like the sound of 104 way better than 91. I guess I'll have to try harder. I'm a corp. pilot and my schedule changes all the time, so my commute has many variables. Some times day, some times night, light traffic, rush hour, some times I can catch a truck going my speed most times not, etc. I drive 56 miles a day, half freeway half town. I havn't been able to keep 100+ for much more than a 100 miles.
The other day when I gassed up after my personal best, a guy driving a Cadillac suv asked how much mpg i got so I asked him to sit in the car and look for himself. I don't think the 91.1 mpg sunk in but he asked what the other number ment (876.4 trip miles). He was very impressed with that.
If you are patient when you gas up you can "stuff" a little more than two extra gallons in the expansion chamber, but use caution when doing this. If you do this make sure you do it in the afternoon when the fuel in the gas station tanks have expanded as much as it is going to and also make sure you can drive the car a substantial distance befor you park it. This might not be a problem every where but here in AZ the temps can stay at a 100+ till about midnight, and the expanded gas station gas could expand even more.
What are your driving conditions?
 

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Sno,
I have an easier time with the mpg because nearly all my driving is interstate. I live in SC and work in DC so I make a weekly commute. On level ground at speed maintaining 90+ is easy. I have had 3 tanks with 100+ and those occured on short weeks when there was even less city driving on the tank. I don't use the expansion tank but one word of caution is that the gas at the station is underground so it will always expand. In July I plan on trying some 145 width tires which may or maynot improve efficiency. I'll let you know. Have fun, Rick
 

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I don't understand why the EPA MPG estimates list the city MPG as being higher than the freeway. In my opinion, that is a perfect example of just how flawed the system is. As much as the IMA helps the Insight in the city, you'll still never achieve close to what you can on the highway.
 

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Nagorak
You must have a CVT transmission as the 5sp has a much higher highway mpg than city. In regards to the driving remember that the faster you go the more air resistance factors into gas consumption. Since this is not a linear effect the CVT cars Prius/Civic/Insight all have higher city ratings. Have fun, Rick
 

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Just got 90.0 mpg/921 miles on my last tank..it amazes me how Richard Reece gets these numbers all the time.. I had to work really hard at it.
 
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Discussion Starter #18
mpg

I know what you mean about having to work really hard to get those numbers. yours are impressive. I just refueled with 8.9 gallons after about 620 miles at 71mpg. I had a 94mpg on a 22 mile segment the other day, with the windows down 8) it was very hard to complete the return at 85mpg, 37mph up one of the hills...

'03 MT no A/C
brft drvr
 

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Just got my personal best for 1-way and 2-way trips, 82.2MPG from my house to YardBirds (9.3 miles) and 77.3MPG after stopping a few places then getting back home (28.9miles) Here I was all excited I was going to get a 70+MPG tank this time, but then I took a trip to a friends house in SF and dropped the average down to 65MPG. I have to laugh at and with myself when I think "Dang! I _only_ averaged 65MPG this tank". Probably could do better, but sometimes I just can't hold the car back at a stop light, it just has to race that SUV that's been tail gaiting me for the past 10 miles :lol:
 
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