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Discussion Starter #1 (Edited)
When I purchased my old well used Insight a year ago, I had no reference on how well it performed with respect to fuel efficiency.

My primary concern was that one or more of the systems were not working well:

- Engine
- IMA battery
- Aerodynamics
- Tires

I have attacked and improved all of these over the past year but still, after a year, there was no firm benchmark to gauge my improvements; especially when driving technique and modifications greatly affect fuel efficiency reported by others (as well as their local terrain and climate).

I just thought of a nice one-number-benchmark that would be good for most of us to roughly but quickly compare Insight performance so that we would know when our car is working well.

Here is the idea:

1. Find a long flat highway along a lake, sea, prairie, or valley floor etc.
2. Drive at a constant speed and note the speed in MPH and fuel consumption in MPG (US GAL.).
3. Increase speed until sustained MPG=MPH..... that is your performance number.

This method should give a good figure of merit for the engine, tires & aerodynamics as a lumped value.

Of course there are other variables like wind speed, temperature, elevation and whether the IMA is charging or assisting during the steady state. These should also be noted. (Turning off the IMA through the "Calpod Clutch Switch" is one way to get a better measurement).


I am in a hilly region currently so I have to drive ~ 200km to get to a nice long flat valley floor.

From an arm waving observation, I am seeing ~ 62mpg at 62mph in this hilly region with IMA active... I should be able to benchmark in the valley in a few weeks.
 

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Here is the idea:

1. Find a long flat highway along a lake, sea, prairie, or valley floor etc.
2. Drive at a constant speed and note the speed in MPH and fuel consumption in MPG (US GAL.).
3. Increase speed until sustained MPG=MPH..... that is your performance number.
It is an interesting idea and in theory it would work. It would certainly provide some benchmark like data for folks to refer to.

As a confirmed hypermiler, I have tried to do performance testing many times. With the gen 1, it is a bit more difficult than you make it out to be. You will never remove driver skill from the equation, even though you think you might, and the tenuous nature of lean burn, at the high MPH crossover point you propose will be a frustration. Finally, general weather conditions, particularly temperature, will remove some of the standardization you desire. You want to encourage a standardized tire pressure, since that is a major variable.

You might also want to "derate" data some for temperature. Not sure just what equation would be used to do that, but the difference between 95F and 75F seems to me to be around 6-10 mpg. Of course, you would want to ban A/C during the test.

I'm just trying to highlight some of the hard to remove variables. I certainly don't want to discourage you from trying to get some data together. In fact, I will contribute my number:)
 

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Discussion Starter #3
Great input JimE! Especially the tire pressure standardization (and to expand on it..brand/model).
 

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Maybe make it an easy "50/50/50": Drive at 50mph, in 50 F weather, with 50 psi in the RE92s....oh, and gas tank at 50% :)
 

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Another idea that would test your tires, aero, alignment, brake drag but not engine or I'ma would be to time a coast from say 60mph to 40 mph in neutral.
 

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Another idea that would test your tires, aero, alignment, brake drag but not engine or I'ma would be to time a coast from say 60mph to 40 mph in neutral.
Yes, coast down measurements have been used before rather extensively by the folks over on ecomodder.com. to test those variables. But, in the end just what do you prove? We already know the answers to those sorts of questions. The RE92 is unbeatable as a LRR tire, the aero drag on the Insight is as low as any street car available, etc. I suppose a very standardized test would maybe highlight brake drag, but again, there are a host of variables not yet mentioned;)
 

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Discussion Starter #7 (Edited)
Wow, I just drove to Toronto from NS in the Insight. It is very flat along the St. Lawrence River.

Yesterday. I did 10 miles straight at 70mph with no AC or Assist. 63.2 MPG (US). Temp ~ 22C, 50PSI.

I'll try again on the way back (and take a few more data points and plot) as we were in a rush and held ~ 70mph most of the way here. a

FYI it is so much easier to keep batteries charged near max in these huge flat areas. If you live in a hilly area and your MPG is not good and your battery's SOC varies a lot, it now seems normal based on my observations. Geography seems to be a BIG factor in how efficient these cars run.
 

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...If you live in a hilly area and your MPG is not good and your battery's SOC varies a lot, it now seems normal based on my observations. Geography seems to be a BIG factor in how efficient these cars run.
I've seen something similar. I mostly drive on limited access highways - but they have frequent up and down grades. Sometimes a mile or more of upgrade, which can pull the SOC display down considerably if I'm using IMA assist. Using IMA assist on a long upgrade can reduce the SOC a lot - sometimes forcing the car into regen at a time when you need all available gasoline hp to move the car.

I've learned to use my CALPOD to limit the drain-down. I try to keep the SOC between about 15-18 bars. Half the bars lit is OK but I avoid going that low. 19 bars (full) is kinda OK but if I brake, it won't regen - it wastes all energy as heat because it won't put any more into the battery.

If I need to climb a long hill in 3rd at 60 mph with the IMA locked out by CALPOD, so be it. That's much better than starting a hill with 40-50% bars lit, and finding myself part way up, with 2-3 bars lit - at which point the car insists on charging the IMA in addition to climbing the hill. Been there done that, and it's not fun.
 
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