recommended approach for efficiency on-highway?

[aqn]

Just to muddy the water some more...

Driving slower: it appears that in all accounts here of people getting pissed because of a slow LEAF, that there was actually room for the following car to pull out and pass the LEAF. I feel zero reluctance to drive at my own speed (keeping a watchful eyeful on the mirrors of course; too many fools texting and driving) if there is room in the next lane for people to get around me. It's not my problem if they're too god damn lazy to make a couple of lane changes. I don't own the road, but neither do they.

Now, if it's crowded and cars are piling up behind me with no where to go, then I'll feel more obligated to not impede forward progress. In that case, I tend to try somewhat to not dawdle.

Coasting in N down hills: by its very definition, in "hilly terrain", a downhill is often followed by an... uphill. Is it better to coast in N then spend more energy getting up the next hill? I like to avail myself to the free energy down hills by drawing about 10 kW (between one to two dots on the eyebrow energy meter) rather than lifting off completely or shifting into N. (Insert stuff here about traffic conditions permitting, common sense, etc.) It's unknown to me whether that is better energy usage-wise than coasting downhill in N, but I do know that I hate drawing 40-50 kW to get up a hill, so I try to generate as much speed as possible going downhill.

 

[Caracalover]

I find a sign that says: "Saudi Arabia Loves You" stops all of these tailgaters from being angry.

We've had a few ideas for bumper stickers here. I may have one made up as a variant of the one you mention. Do you actually have that as a sticker on your car and does it actually generally defuse the anger?

I have written it in the dust on my back window, and have had people tell me they like it. As for dissipating anger, I have said it (Face to face) to angry gear heads when volunteering with Plug In America, and I have seen them visibly alter thier attitude, one particular case actually returned with another person and although they didn't come over and talk with me again, they did listen in while I was talking to others, so I would say that it does work.

 

[Caracalover]

Just to muddy the water some more...

Driving slower: it appears that in all accounts here of people getting pissed because of a slow LEAF, that there was actually room for the following car to pull out and pass the LEAF. I feel zero reluctance to drive at my own speed (keeping a watchful eyeful on the mirrors of course; too many fools texting and driving) if there is room in the next lane for people to get around me. It's not my problem if they're too god damn lazy to make a couple of lane changes. I don't own the road, but neither do they.

Now, if it's crowded and cars are piling up behind me with no where to go, then I'll feel more obligated to not impede forward progress. In that case, I tend to try somewhat to not dawdle.

Coasting in N down hills: by its very definition, in "hilly terrain", a downhill is often followed by an... uphill. Is it better to coast in N then spend more energy getting up the next hill? I like to avail myself to the free energy down hills by drawing about 10 kW (between one to two dots on the eyebrow energy meter) rather than lifting off completely or shifting into N. (Insert stuff here about traffic conditions permitting, common sense, etc.) It's unknown to me whether that is better energy usage-wise than coasting downhill in N, but I do know that I hate drawing 40-50 kW to get up a hill, so I try to generate as much speed as possible going downhill.

All good points, as for muddy water, that would really impact the range, so I would stick to the clean water whenever possible.

As for the coasting to gain speed versus gaining the regeneration energy. You lose kinetic energy to wind resistance when you exceed 37 or so MPH. (Nissan says that is the best speed.) So if you can do 37 MPH up the next hill, it would likley benefit you to regenerate the energy and keep your speed down. Of course if the air is dense, a head wind, etc, etc, it will impact how much of a difference you will see. In most cases it will not matter much either way. If you are rolling down hill in excess of 70, you should gain some energy rather than go faster. If you truly need the range, then staying off the highway would be the better option, and stick to the 37 MPH when possible. You can double your range if you don't have to stop too much, so a few extra miles by taking the longer, lower MPH route should be considered.

 

[Caracalover]

Not watching traffic should NEVER be a policy, as someone here suggested. Always watch the rear, side, and forward traffic, and remember not only your life is in the balance, but a mother's child is also in your hands.

Oh by all means watch the traffic coming up behind you.. just ignore that SUV approaching you at a speed differential of 15mph.. dont speed up and if you get annoyed just light up your brake lights for a sec, please do this only on the right lane. Flip up your rearview mirror if you live in fear but obviously you are fearless if you are tailgating a semi.

The truth here that you people cant stand driving at 55mph and blame the drivers behind you or you dont want to "inconvenience" them. Whats the hurry?

Are drivers in CA so distracted that they will run into the back of your car at 15mph?

Hitting your brakes should not be your reaction to someone trying to pass on the right where I come from. It is legal to pass on the right in CA, and almost all the exits are from the right lane. These exits have been modernized in most cases to handle higher speed traffic. This is done in part to aid traffic flow, and one slow poke can have a large impact on thousands of drivers. Honest. So that would be the reason to hurry, and not inconvenience them. Also, a large SUV is going to burn more fuel parked for an hour than you use in your Leaf to go 100 miles. For them, the speed travelled really doesn't add to the fuel economy much, so help them get where they are going, don't impede them.

If the traffic to the left is moving so slow that passing it on the right is appealing, than perhaps moving to the left and leaving the right lane clear would be a better option. With the torque in the Leaf you can easily merge in and out and the drafting benefit will almost negate the power used to do so. When the larger vehicle goes by on the right, merge back in and take the elimination of the wind resistance that comes from following.

For an example of why you might want to be a nice driver, here is a short video.

http://www.facebook.com/#!/photo.php?v=10151072388436895&set=vb.551396894&type=3&theater" onclick="window.open(this.href);return false;

 

[aqn]

Coasting in N down hills: by its very definition, in "hilly terrain", a downhill is often followed by an... uphill. Is it better to coast in N then spend more energy getting up the next hill? I like to avail myself to the free energy down hills by drawing about 10 kW (between one to two dots on the eyebrow energy meter) rather than lifting off completely or shifting into N. (Insert stuff here about traffic conditions permitting, common sense, etc.) It's unknown to me whether that is better energy usage-wise than coasting downhill in N, but I do know that I hate drawing 40-50 kW to get up a hill, so I try to generate as much speed as possible going downhill.

As for the coasting to gain speed versus gaining the regeneration energy. You lose kinetic energy to wind resistance when you exceed 37 or so MPH. (Nissan says that is the best speed.)

If I read that right ("lose kinetic energy to wind resistance when you exceed 37 or so MPH"), I still do gain kinetic energy above 37 mph, but the gain becomes smaller as the speed becomes larger? I think that's right, because if I throw my LEAF off a cliff, it'll be gaining speed (and kinetic energy) up until it hits terminal speed or the ground, which ever comes first . If so, I'm still gaining kinetic energy, albeit in smaller increments.

So if you can do 37 MPH up the next hill, it would likley benefit you to regenerate the energy and keep your speed down.

In my case, many of said hills are on semi restricted access "high speed" roads with speed limit of 55-60. I would do 37 or less up a hill if there is nobody behind me for a way. Typically though, unless it's really late, there'd be cars behind me. They would find it alarming to have someone backing up to them from 60 down to 37, so I'd prefer to not slow down too much.

Of course if the air is dense, a head wind, etc, etc, it will impact how much of a difference you will see. In most cases it will not matter much either way. If you are rolling down hill in excess of 70, you should gain some energy rather than go faster.

True, I can regen and gain some energy, but then it'd cost me more going up the next hill since I'm carrying less speed. The thing I have not felt the need or urgency to figure out is which approach yields the better net, energy usage-wise.

If you truly need the range, then staying off the highway would be the better option, and stick to the 37 MPH when possible. You can double your range if you don't have to stop too much, so a few extra miles by taking the longer, lower MPH route should be considered.

I don't need the range (which is why the LEAF suits me great!). These are not highways; there are usually no lower-speed side roads that does not add significantly to the trip's distance. I just like to know whether (and to think I'm doing) the best thing energy usage-wise.

 

[Caracalover]

The thing I have not felt the need or urgency to figure out is which approach yields the better net, energy usage-wise.
I just like to know whether (and to think I'm doing) the best thing energy usage-wise.

LOL, on the gaining kinetic energy part I deleted...

The argument as to which yields the better net will vary on the hill, rolling resistance, head wind, temp, etc. etc. No way to say either is better as a general rule - too many variables. Over 70 I am pretty sure you are better off gaining the regen, but below that it is hard to compute. I know I enjoy seeing if I can get enough speed up on the down hill to roll to the top of the next hill and then coast down the other side. My Sunday commute allows for this on a regular basis. I take a mountain road that has a 55 top speed that kills people that try to maintain it. Easy to do 30 when the cautionary signs tell you that is the safe speed. BTW the yellow signs are suggested speeds, the white signs are enforcable speeds.

 

[jlsoaz]

Related to these questions of whether to coast in N:

- Does anyone know if driving in D rather than in ECO would sometimes result in greater energy economy? I'm wondering if sometimes D leads us into neutral where ECO might put on the regen brakes and bleed away speed? Or is D always pushing to use energy rather than opting for neutral?

- In general, I'm wondering if there is potential for saving energy with some interesting new approach to driving involving being in neutral more of the time. However, I don't myself want to go around doing micro-switches in and out of drive, I think I'm just wondering about this in a theoretical way, and maybe someday if Nissan engineers it in?

 

[LEAFfan]

Two car lengths at 65 mph :shock:

I prefer three seconds or 264' at 60 mph.

Agree. I like the enthusiasm and recommendation for drafting large semis pushing the air out of the way, but following too closely for safety is not good, so I wonder if there is some balance to be struck there, sacrificing some of the energy efficiency gains for the sake of safety and respect for other drivers, but still following closely enough to get some energy-saving-benefit. I don't know if the air further back would be conducive to saving energy or not. It might be necessary then to identify a truck at 55 or 60. ...

Everyone please take a good look at the back end of a semi -- specifically the area your vehicle would be striking in the event of a collision. It's not very forgiving.

If you're LUCKY, there's a steel beam there to prevent your vehicle from diving under the truck and decapitating you. And if you're really lucky, the beam is adequate to the task instead of having been slapped on for bare compliance.

I would strongly recommend not trying to get an aero advantage by riding closely to the back of a semi. Though few people follow it, the general rule for safe following distance is 4 seconds. At 60 mph that's over 350 feet of following distance. And it's a good idea when following something as unforgiving in a crash as a semi truck.

We were taught one car link for every 10mph.

 

[Caracalover]

Related to these questions of whether to coast in N:

- Does anyone know if driving in D rather than in ECO would sometimes result in greater energy economy? I'm wondering if sometimes D leads us into neutral where ECO might put on the regen brakes and bleed away speed? Or is D always pushing to use energy rather than opting for neutral?

- In general, I'm wondering if there is potential for saving energy with some interesting new approach to driving involving being in neutral more of the time. However, I don't myself want to go around doing micro-switches in and out of drive, I think I'm just wondering about this in a theoretical way, and maybe someday if Nissan engineers it in?

I believe that in many cases ECO slows the vehicle too much, therefore requiring you to use more power to regain speed lost, and therefore it is as you suspect, D can be useful in achieving a greater economy.

Watch the power meter when it is safe to do so and play with all three settings. N, D, and Eco all have thier uses, and if you feather your foot well in ECO it is likley the most reliably economical, although I can't do it. I drive too much so I shift into N a lot as a habit, going back into D to slow a little, or ECO to slow a lot. For driving uphill I am usually in D, since I like the ease of access to the power. If I need to hypermile, I sometimes use ECO for take offs as it is easier to regulate my energy use.

The greatest energy economy will be had if you keep your energy use at 0. Eco mode can take you below that too much, and D can take you above it too easy. N keeps you at that level.

 

[jlsoaz]

I believe that in many cases ECO slows the vehicle too much, therefore requiring you to use more power to regain speed lost, and therefore it is as you suspect, D can be useful in achieving a greater economy.

Watch the power meter when it is safe to do so and play with all three settings. N, D, and Eco all have thier uses, and if you feather your foot well in ECO it is likley the most reliably economical, although I can't do it. I drive too much so I shift into N a lot as a habit, going back into D to slow a little, or ECO to slow a lot. For driving uphill I am usually in D, since I like the ease of access to the power. If I need to hypermile, I sometimes use ECO for take offs as it is easier to regulate my energy use.

The greatest energy economy will be had if you keep your energy use at 0. Eco mode can take you below that too much, and D can take you above it too easy. N keeps you at that level.

Hi Caracalover:

Good to get your points here.

With respect to driving on highway, I am wondering if there might be real potential here for Nissan's engineers to seek to replicate your efforts and those of others and create a revision of the existing ECO mode, or different type of ECO mode, for energy saving under circumstances (often but not always highway circumstances?) where the existing ECO mode might have a tendency to bleed off too much (or any?) energy under circumstances where it will be needed just a few seconds, or fractions of a second down the road.

I noted that Mitsubishi engineers did make a modification at some point that allowed their vehicle to get a decent percent more miles out of the same kWh. I wonder if the modifications were in this area or in some other area?

I found yesterday that while in cruise control at 65, I was able to switch between ECO and D. However, I did not figure out how to switch into neutral while driving. Can this be done? Is it considered unsafe to try these things? I became a bit concerned about inadvertently trying to switch to R while driving forward, but am hoping that particular one has been rendered not possible by Nissan engineering. (Note, my other car is a stick-shift for many years now... I am no expert but just clarifying that the concept of switching gears or going into neutral is not foreign to me).

I have also got to wondering if part of engineering or brainstorming energy-saving improvements in this area (including if in cruise control) might involve some sort of predictive ability in the car to see ahead regarding going uphill and downhill. Is it best to coast in N toward the bottom of a hill in order to build up a bit of speed for going uphill? Might there be a way to build an option into a cruise control to be flexible by 2 or 3 mph above or below the desired speed for momentary hill tops and bottoms? I was thinking a bit about riding a bike.... in that situation one would have the option of making instant adjustments for effort to save energy, but a car in cruise control probably isn't given that option.

Note that all this is not to ignore the other recommendations given in this thread for highway energy savings (going slower, avoiding highways where possible, following another vehicle at a safe distance to reduce some wind resistance... I have also found that a big one for me has been checking tire pressure and inflating to the max recommended).

-

Anyway, a completely separate topic here to me is not to do with highway energy savings so much as understanding automotive propulsion energy savings in general, in terms of frequency of push (for want of a better term). We see IC vehicle manufacturers have designed some engines to shut down cylinders .... where fewer explosions per second will be sufficient to keep the vehicle rolling at the desired speed. If I recall from physics classes, while f=m*a is the basic equation for calculating acceleration, there was another much more obscure equation concerning "impetus".... sort of an alternative way to look at speed or attaining speed? Also seemingly relevant were the discussions of elasticity.

With IC engines, traditionally, the application of more or less energy has been a fairly straightforward process (press the pedal to deliver more fuel to the engine). There may be some sophisticated modifications built into this over the decades. I suppose one example would be the number of cylinders example I gave. I guess there are a few points here to lay out, perhaps in a new thread, with one of them being to question just the basic idea of what we get when we press what we have thought of as the "accelerator" or "gas" pedal. There is also the related question of what we get when we let off the "accelerator" pedal. Do we get "engine braking" (when the vehicle is still in gear) and-or reduction in fuel flow, or continued fuel delivery (when something like cruise control is engaged) ... etc.?

I'm sure that Nissan engineers and others have explored and optimized for some of the potential energy savings (avoiding engine or motor breaking for example?) but perhaps there is more to be done..... I suppose one example is provided by Caracalover's and others' efforts with drive settings while on-highway and (apparently) getting some extra and useful energy savings from those efforts.

 

[LEAFfan]

Josh, if you're going 7mph or higher, you can throw it in R and it will instantly go to N. If you put 41psi in your tires, you will be able to coast much farther. When I'm going 65mph and reach the beginning of an exit (more than a quarter mile), I coast in N all the way to the light which really boosts my m/kW h. With the tires at 41, you dont lose that much speed so it's very safe.

 

[jlsoaz]

Josh, if you're going 7mph or higher, you can throw it in R and it will instantly go to N. If you put 41psi in your tires, you will be able to coast much farther. When I'm going 65mph and reach the beginning of an exit (more than a quarter mile), I coast in N all the way to the light which really boosts my m/kW h. With the tires at 41, you dont lose that much speed so it's very safe.

Thanks.

With respect to tire pressure, a few weeks ago I got a low tire pressure warning on one (I thought) of the tires, on a cold night, and the next day I was able to find a station to put pressure in. I decided to bring all the tires up to max at that time, and I haven't regretted it, as far as efficiency goes (not a highway-efficiency-specific measure of course).

With respect to coasting in neutral, when I was taught to drive stick, this included a general "avoid coasting in neutral" lesson, for safety reasons I guess, and I have stuck to that when driving stick, but will consider changing a bit with the Nissan under occasional low-traffic conditions, we'll see.

 

[DarkStar]

I found yesterday that while in cruise control at 65, I was able to switch between ECO and D. However, I did not figure out how to switch into neutral while driving. Can this be done? Is it considered unsafe to try these things?

Yes, just hold the selector to the left for a couple of seconds (not toward D/Eco or R) and the Leaf will switch to Neutral, move the selector back to Drive (or Drive a second time for Eco) to move back. From a safety perspective, there is no reason why Neutral would be any less safe as the only thing it prevents is acceleration and braking is not affected (other than no regenerative braking occurs).

 

[jlsoaz]

I found yesterday that while in cruise control at 65, I was able to switch between ECO and D. However, I did not figure out how to switch into neutral while driving. Can this be done? Is it considered unsafe to try these things?

Yes, just hold the selector to the left for a couple of seconds (not toward D/Eco or R) and the Leaf will switch to Neutral, move the selector back to Drive (or Drive a second time for Eco) to move back. From a safety perspective, there is no reason why Neutral would be any less safe as the only thing it prevents is acceleration and braking is not affected (other than no regenerative braking occurs).

Ok, thanks for the response.

I'm really hoping that Nissan engineers can follow these and other threads, and their own lines of inquiry, and determine if there might be something useful here for them to implement as a fool-proofed automated feature for all to use (e.g.: "ECO-highway".... something like that.).

 

[TomT]

In many states, it is illegal to do so. Of course, those rules were written some time ago..

With respect to coasting in neutral, when I was taught to drive stick, this included a general "avoid coasting in neutral" lesson, for safety reasons I guess, and I have stuck to that when driving stick, but will consider changing a bit with the Nissan under occasional low-traffic conditions, we'll see.

 

[jlsoaz]

Interesting, I didn't know that. Over the years, as I have contemplated the efficiency gains to be had by moving toward electrification, the big two for me were regen braking and eliminating the energy wasted during idling, but underneath that I think there have been others. I'm not sure if they were always apparent to me. Perhaps one is "engine braking" (for want of a better phrase) when maintaining speed is actually desired. If so, then putting the car in regen braking posture when this is not optimal might in large part defeat the efficiency gain to be had.

If manually shifting to neutral, such as suggested here, for certain quick coasting periods, is not recommended or is illegal (due to safety aspects?) then I wonder if this would give added value to Nissan looking into it as an automated option for some situations. In fact, I wonder if maybe ffv manufacturers already do this with the automatic transmissions on their internal combustion vehicles under some quick situations?

In many states, it is illegal to do so. Of course, those rules were written some time ago..

With respect to coasting in neutral, when I was taught to drive stick, this included a general "avoid coasting in neutral" lesson, for safety reasons I guess, and I have stuck to that when driving stick, but will consider changing a bit with the Nissan under occasional low-traffic conditions, we'll see.

 

[Caracalover]

In many states, it is illegal to do so. Of course, those rules were written some time ago..

With respect to coasting in neutral, when I was taught to drive stick, this included a general "avoid coasting in neutral" lesson, for safety reasons I guess, and I have stuck to that when driving stick, but will consider changing a bit with the Nissan under occasional low-traffic conditions, we'll see.

It could be argued that there is no "neutral" in the Leaf, as it has no transmission. A fully charged Leaf brakes as if it is in N, so no law is being broken when putting the vehicle in the N position. I would say N stands for No energy flow, and that is a closer description for what it is than Neutral.

I would not advise a long mountain descent with a fully charged battery, as the heat from the brakes may not get you to the bottom safely. Should you find this to be an issue, jack rabbit the vehicle where safe (Use 80KW), and brake hard enough to not engage the regen until you have some reliable regen slowing.

Gaining speed through coasting is an eerie feeling if you are not able to slow the vehicle except with the brake. The Leaf regen is a lot of fun on mountain roads. I typically can alternate between N, D, and ECo modes to drop over 3000 feet and never touch any pedal.

Unlike a vehicle with a transmission (or stick), the Leaf will always go back into D or ECO. In a transmission vehicle, the gears have to be turning at the same speed to get them to align (shift), and judging that is something most people can not do well (nor can an automatic transmission). The clutch is an aid to get this job done (Which puts you in neutral, so if that is a law, you break it every time you shift). You can do it without a clutch if you judge it right. Selecting the right gear is why Neutral is a bad idea in a stick shift. Imagine doing 70 and dropping into first gear. Even if the car survives the skid mark on the road would not be safe.

Neither of these issues exist in the Leaf.

 

[TonyWilliams]

Here's my description of "N" that folks seem to get. First and foremost is "no brakes" concept. If you need the brakes, you probably weren't planning ahead well enough.

Granted, if you must stop at the bottom of a hill, absolutely regen down the hill, since the LEAF isn't going to be stopped by then, and you'll no doubt need mechanical (energy wasting) friction brakes at the end.

If you are on a level road, or uphill and can coast in "N" to a stop, that is the best efficiency you can get. The power you didn't use to propel the car prior, and then require regen to stop, is the savings.

You can coast in N down a hill if there's no stop at the end, or it goes uphill. The only caution on coasting downhill is don't let the speed get much over 60mph, since the energy is going increasingly to overcoming drag. You might as well use just enough regen to keep the speed under 60mph.

Any time you must regen can only be offset in efficiency by the alternatives... you can't get stopped for instance.

I don't recommend going over the manufacturer's tire pressure rating, but do recommend the maximum allowed.

Hope this helps.

 

[planet4ever]

From a safety perspective, there is no reason why Neutral would be any less safe as the only thing it prevents is acceleration and braking is not affected (other than no regenerative braking occurs).

OK, maybe I'm just "old school", but I disagree strongly with your safety assertion. You are right that neutral prevents acceleration; the accelerator pedal is dead while in neutral. And precisely there is the first safety problem. There are times when the safest way out of a problem (such as something on the road dead ahead) is to accelerate and merge into another lane. You are also right that there is no regen, or in old school terms, engine braking. And that is the second safety problem. If your brakes overheat or fail for some other reason you become a runaway freight train.

Yes, neutral can squeeze a little extra distance out of your battery, but I'm far more interested in squeezing a little extra safety out of my car. I never use neutral when on the road.

Ray

 

[DarkStar]

From a safety perspective, there is no reason why Neutral would be any less safe as the only thing it prevents is acceleration and braking is not affected (other than no regenerative braking occurs).

OK, maybe I'm just "old school", but I disagree strongly with your safety assertion. You are right that neutral prevents acceleration; the accelerator pedal is dead while in neutral. And precisely there is the first safety problem. There are times when the safest way out of a problem (such as something on the road dead ahead) is to accelerate and merge into another lane. You are also right that there is no regen, or in old school terms, engine braking. And that is the second safety problem. If your brakes overheat or fail for some other reason you become a runaway freight train.

If a driver feels like they need to be able to accelerate for safety, I would first suggest they look at changing their driving style first. I've never had to accelerate to avoid a collision and have never seen or been given driver education instruction to do so.