Efficient Driving in the iMiEV

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Aerowhatt

Well-known member
Joined
Jan 28, 2015
Messages
446
So I've been waiting along time for this comparison. Reading others RR numbers after full charge scattered throughout many threads I've been remiss to crow about mine since I simply couldn't understand definitively why they would be so good consistently. Maybe there was something amiss with my cars systems, but no.

Yesterday I had the opportunity to have my wife drive the car all day, (she resist driving it, mostly for her own credible reasons). But in this case it was the lesser of two evils. All in all she made six trips (three round trips). Two (of six) legs she was driving with me in the passenger seat. The other four alone in the car. I was stealthily watching every nuance of her throttle and brake use and overall driving style. Now she is no slouch when it comes to good fuel economy in an ICE. She bests the EPA rating in her Honda Fit (5 speed manual) by 6 mpg regularly. All that running around left the 'I' with four bars and 15miles on the RR meter. A perfect chance to compare our efficiency since I drive those same parts of town frequently. Give or take a couple of city blocks.

After a full recharge the RR meter was at 64 miles (not bad right?).

I've been keeping track for months and my morning RR ranges between 84 miles and 98 miles with a few outliers lower like the 72 mile RR after recharging from taking my wife to have her knee looked at, after hurting it surfing in Costa Rica, in January. But I drove her there and did two hours in the parking lot running the heat steadily (31F outside partly cloudy) doing some work on my laptop.

So what then achieves the almost 25% increase in efficiency for my approach to driving the car over hers.
My 19 year old son would say I drive more aggressively than his mom. So that's not it.
I've concluded it's not what you do, but how you do it that matters!

1. I'm super steady on the throttle none of the constant on and off, on and off, that many drivers do by default.

2. I'm super smoooooth with the throttle changes I do make.

3. I accelerate briskly to be sure but rarely push the power meter very much past the second mark to do so.

4. I "brake" long and steady to stops rarely pegging the power needle in the regen zone.

5. I drive well ahead of my position which allows me to drive proactively to upcoming conditions instead of reacting to them later when I'm upon them.

Number five is the critical one in my mind since it enables one to do most of the others. I read a study once where drivers were gauged. (one of those eye position instruments) they deemed that most drivers drive a little under 100 ft from their hood. Some measured significantly less. I drive more like 400 to 600 feet in front of my position, Even farther on the freeway. I was taught this in a defensive driving course taught by a very convincing, rational, smart instructor. It pays off in other ways too. Like avoiding traffic issues instead of sitting in them. Knowing whats ahead lets one catch more free lights and always maximize regen recovery from ever stop that can't be avoided.

Observing my wife drive the 'i' she was on and off the throttle constantly. and regen/braking later than I would using more friction braking. Even braking hard with just regen (B mode pegging the needle) is significantly less efficient. High rate charges (regen) and discharges (needle pegged acceleration) waste power more than lower rates. Just as power conversion at maximum rates (motor and controller) is less efficient.

Sure I pegg it once in a while getting by the SUV's to be first up the ramp onto the freeway. But most ICE's can be beat with 2 1/4 notches on the power meter.

I hope these proven strategies help some have more range and just as much fun leading the pack around!

Just as s side note I went to the DMV this morning a 15.2 mile round trip and started with my wife's 64 mile RR and returned home with the RR showing 63 Miles :)

Aerowhatt
 
Aerowhatt, "by Jove, I think you've got it"! Good observations contrasting driving styles.

The variable that perhaps you don't have that we experience around here is that while you're looking 1/2-mile down the road at the red traffic light that you're planning on timing to hit perfectly as it hits green, a bunch of yahoos jump in front of you and rush up to that traffic light and stop dead and block you.

For myself, having been obsessed with hypermiling my Gen1 Honda Insight (77mpg lifetime when it was totalled when hit by a drunk driver) and the first year or so of i-MiEV ownership, nowadays I only hypermile when taking long-distance trips when I need the range. My electricity is free and, although wear and tear on the battery may be higher when leadfootin', I'm more into counteracting the perception that EVs are slowpokes.

BTW, if you ever get up to beating the Maximum Range Remaining http://myimiev.com/forum/viewtopic.php?f=28&t=329, currently at RR=109miles, be sure to take a photograph of your dashboard and get into our record books.
 
JoeS said:
Aerowhatt, "by Jove, I think you've got it"! Good observations contrasting driving styles.

The variable that perhaps you don't have that we experience around here is that while you're looking 1/2-mile down the road at the red traffic light that you're planning on timing to hit perfectly as it hits green, a bunch of yahoos jump in front of you and rush up to that traffic light and stop dead and block you.

For myself, having been obsessed with hypermiling my Gen1 Honda Insight (77mpg lifetime when it was totalled when hit by a drunk driver) and the first year or so of i-MiEV ownership, nowadays I only hypermile when taking long-distance trips when I need the range. My electricity is free and, although wear and tear on the battery may be higher when leadfootin', I'm more into counteracting the perception that EVs are slowpokes.

BTW, if you ever get up to beating the Maximum Range Remaining http://myimiev.com/forum/viewtopic.php?f=28&t=329, currently at RR=109miles, be sure to take a photograph of your dashboard and get into our record books.

I'm definitely doing my part to change the perceptions of EV's. I put "electric" in chrome letters on the hatchback. The placement makes it look like the factory did it. Often I see someone behind me, or in close traffic reading it and the pointing it out to their passenger. Next acceleration opportunity I put a bunch of daylight between us. We do a lot of short freeway "hops" here too, so lots of on ramp races, the 'i' almost always wins.

I kind of (have learned too) enjoy the Yahoos in front of me. I call it psychic chess. Where you must correctly predict your opponents moves before they make them in order to "win" :)

I'm pretty convinced at this point that a 2014 model has different software than the 2012. It won't go over 98 miles RR. No matter what I try :roll:

Aerowhatt
 
Aerowhatt said:
Even braking hard with just regen (B mode pegging the needle) is significantly less efficient.

Do you drive exclusively in one mode most of the time? If so, which? I used to run the gates when I first got my Meepster; always trying to eek out every drop of efficiency I could. After several months of driving like that, I got tired of it. I settled on putting it into B mode and leaving it there. I now use the go-pedal to moderate my power and regen rather than the drive mode.
 
RobbW said:
I settled on putting it into B mode and leaving it there. I now use the go-pedal to moderate my power and regen rather than the drive mode.
I've done that from day 1. I perfected the technique years ago on my hydrostatic diesel garden tractor - Never use the brake on that thing at all. On the i it's necessary to use the brake pedal to come to a complete stop, since the 'creep mode' prevents it otherwise. The wife has gotten even better at it than I am - She regularly make the 15 mile round trip to the gym and back taking ony 10 to 12 miles off the RR meter

Don
 
I drive in ECO all the time (one exception is when I make the trek to 7 Springs and am climbing mountains, then I use D to save some foot fatigue). I'll use N and all three drive modes to vary regen without touching the brake pedal, and every once in a while I'll use B as a "Boost Mode", taking advantage of the varying throttle maps.

Every once in a while I'll time it just right and can roll up to certain stop signs and stop lights without touching the brake at all and come to a stop :cool: .
 
Unless I need to stretch the range I like B mode. Also like to leave all but the boy racers in my rear view when launching from a traffic light :mrgreen: At least up to 40 mph or so, I don't need to drive as fast in general in the Miev but do like the initial surge. On longer drives I'm perfectly happy being a bit conservative until there is an extra 15 miles or so on the meter then pick up the speed.
 
I used to run the gates. As I would approach a stop, I would bump up into N and coast for as long as I could. Then I'd drop down into D, then Eco, and finally B for the progressively more aggressive regen. I'd wait until the last moment possible to finally use the service brake to come to a complete stop. For whatever reason, I thought that was the best way for me to get the most efficiency out of my Meepster. After several months of driving like that, I got burned out and tired of the constant attention it required for the (in actuality) meager gains I was rewarded. So, I spent a week test driving in one mode only each day of the week. I used my work commute as the test route since it pretty much was exactly the same every single day. I settled upon B mode after that and have been driving in B mode exclusively ever since.

The funny thing was that after I started driving in B mode exclusively, I found out I actually got slightly better efficiency compared to my previous running of the gates!

Now, for some reason, I am back to questioning which is the best driving mode for my commute and style of driving. I don't know if I'm just getting bored of B mode, or if there is a little voice in the back of my head wondering if there is an even more efficient driving style in my Meepster, or maybe my experimental side has just been reignited for some unknown reason. Who knows?! But I'm thinking about testing my different driving methods again. And this time, I have Canion to provide some actual real data for my experiments.

Now if I could just get my lazy butt to actually commit to this experiment! Part of me just keeps questioning whether all the effort is really worth it? Do I really want to go through the rigors of testing for what may ultimately result in a puny 0.3 miles per kWh increase in efficiency?

Currently, my usual morning RR after charging is in the mid 70s, which isn't all that great of a number. Especially when I see other iMiEV owners posting numbers in the 80s and 90s on a regular basis. My problem is that my regular commute does not lend well to the driving style that is needed to hit those kind of RR numbers. I'd be likely to get shot in a road rage incident if I started driving *that* efficiently here in the Chicago suburbs! However, if simply changing the drive mode that I use could help bump my RR numbers at least up into the 80s, I'd be happy with that.

So, would the drive mode have that much of an effect on your efficiency? Or is it really all in your personal driving style? At this point, there really isn't much more I can do to make my driving style more efficient here in the Chicago suburbs. I'm already riding a fine line with my fellow commuters. I see the same commuters every day, and they definitely recognize me. Whenever we are stopped at one of those intersections where the two lanes merge down to one lane after the intersection, everyone always tries to burn it off the line and beat me to the merge because they know they don't want to get stuck behind me!

I don't jackrabbit off a stop. I maintain a nice, even, easy acceleration. I try not to let the power line go over the first line when accelerating. If I ever need to give it a bit more juice than that, I try not to go above the second line. I do not speed. I maintain a large buffer between me and the car in front of me. I gently coast down to a stop using the go-pedal to modulate between coasting and regen. What more can I possibly do to improve my efficiency without enraging my fellow commuters? And would any increase in efficient driving be significant enough to really notice?
 
RobbW said:
...What more can I possibly do to improve my efficiency without enraging my fellow commuters? And would any increase in efficient driving be significant enough to really notice?
Nothing, and no, respectively. I've come to the conclusion that in everyday driving there is no need to hypermile and it's more fun to show off the i-MiEV's backsides to the ICE slugs. I can drive very efficiently when I need to, but that is rarely the case. More on this topic:

http://myimiev.com/forum/viewtopic.php?f=28&t=287
 
We use mostly the ECO mode here in Rockford. This is just an amazing car with the regenerative braking.
The other day for instance we drove to the Airport. We started with 26 RR, and got there with 24 RR.
The airport is 11 miles from our house. Great!
This will come in handy on our 5,000 mile round-trip to Santa Monica in March!
 
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