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Discussion Starter · #21 ·
It makes sense if you think about it. If you didn't accelerate and depending on how long of a downhill stretch your battery would become full quickly. Once it becomes full your engine fires up to burn off the regenerated energy instead of storing it in the battery. By accelerating when needed you're preventing the battery from reaching max capacity and allowing yourself to coast down in EV mode as long as possible.
The scenario you’re describing also makes sense, but that’s not what was happening in this case. Most downhill stretches lasted 30 seconds or less in my case, so the battery never reached past 75% full, whether I coasted or gassed and banked.

After observing the fuel economy reading for a few months I eventually realized that the most emphatic MPG gains happened after stretches of downhill + regen, so I experimented with artificially making that happen whenever I could and that was the result.
 

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Well gravity plus your acceleration is pushing you downhill faster. The regenerative braking increases the rate of recharge the faster you're going. At least to a certain point cause Honda definitely set a threshold to prevent the battery from overheating. So in the end you're most likely making more energy than using on that stretch.
 

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Wow. What a great idea! I'll have to try it!!

My thinking is that the small amount of energy used to accelerate gives a much greater than usual speed increase, due to gravity's extra push. Thus, as the braking begins you got much more energy coming out than was put in. The mpg increase comes from more efficient capture of the potential energy located in the cars' movement from top of a hill to the bottom.

Another possibility is the mpg increase for most of the trip was due to a tail wind, and not the downgrade. Possible I suppose, but I prefer the other explanation.
 

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Discussion Starter · #26 ·
The mpg increase comes from more efficient capture of the potential energy located in the cars' movement from top of a hill to the bottom.
Yep, that’s my guess too. Seems that downhills are a sort of “multiplier” of any acceleration you put in. Presumably there is a point of diminishing return; I wouldn’t expect that flooring it on a downhill would be very efficient, but a light tap goes a long way for very little cost.

Another possibility is the mpg increase for most of the trip was due to a tail wind, and not the downgrade. Possible I suppose, but I prefer the other explanation.
I was watching the mpg gauge pretty closely. Performance was pretty standard for the entire trip, except for the very noticeable bump after using the above strategy. Very interesting indeed!
 

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I recently got a record high (for me) 78.8 mpg for a tank full. My prior record high was 77.x. I think that 78 figure is a false high because I suspect slightly less than a full tank at fill up (due to 1.5 mpg spread between car's mpg and calculations from gas pump and odometer. Normal spread is 0.75 mpg).

It has been sunny-er and warmer prior to last fill up. Some daily 50 mile drives have been above 80 mpg when 78 - 79 is ordinarily the best I can do. I got a one time personal best 83.x last year when the traffic gods, wind speed, direction, and battery warming sunshine were all in alignment. Also I'm up to 46k miles, the oem tires are getting worn, and that can help mpg.

I agree with Andrew 28 that a large number of uncontrolable driving conditions make a big difference. But still, there is a lot one can do, to better one's mpg within those conditions. For example awrxmcr has a higher lifetime mpg than I (70 mpg), but all his Insight driving seems to be below 50 mph. He uses other vehicles for highway trips.
I bought my honda insight 2021 last year . I have drove 2500 miles and my mpg is 42 . Most of my trips are very short under 5 miles . I have come to know that short trips kill mpg . Can someone please guide me to achieve high mpg for these short trips . If it is possible to drive in ev mode for very short trips.
 

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I bought my honda insight 2021 last year . I have drove 2500 miles and my mpg is 42 . Most of my trips are very short under 5 miles . I have come to know that short trips kill mpg . Can someone please guide me to achieve high mpg for these short trips . If it is possible to drive in ev mode for very short trips.
I have the same challenge, and haven't found much of a solution.

For me the big mpg killer is the engine warm up process when first driving the car in the morning. That same warm up process happens during the day, when I turn off the car for a brief period, even though its warmed up after lots of driving. The ev system is very sensitive to temperature. It likes warmth, but not hot. So I park in a place where I can catch the morning sun (if there is any) and warm up the interior and HV battery. This leads to slightly faster recharging and possibly shorter engine warm up process.

It may help to do your long trip first, to get the wheels turning during the warm up process, where the engine really is cold after sitting all night. Then, do the short trips, while the engine is actually warm, from previous driving. Keep pushing the ev button on the center console, its telling the computer you wand ev mode !!
 
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