There seems to be a growing resentment from the LEAF community from new drivers slowly realizing that E Pedal is not very efficient. Its not hard to understand how they got that impression since E Pedal is capable of regen levels more than 50% higher than B mode. More regen means more range recovered, right? But that is a two sided street and you won't like the view. So why do we have E Pedal and what is the best mode to drive in for best range? To answer that, we have to clarify several different mitigating factors and even after addressing those factors, the key takeaway will continue to be YMMV.
E Pedal
E Pedal was added to the Gen two LEAF when launched in 2018. It enables one foot driving where you could conceivably drive all day without moving your foot from the accelerator only touching the brake pedal to start the car. E Pedal does this by a combination of increased regen approaching 60 kW and friction braking which can bring your LEAF from 40 mph to a complete stop in less than a block. The amount of friction braking varies by SOC and speed. At street level speeds, friction braking kicks in at very low speeds only so its mostly regen slowing you down. The only exception to the rule is when the SOC is high enough that regen is limited. Friction braking increases at high SOC to make the "drive feel" consistent. If you had an older LEAF (or a new one) fully charged, you know that the car seems to move a lot faster until some of that charge is used up. This is due to little/no regen and the considerable difference in how the car drives can be a bit disconcerting to some.
B/D
D mode is probably the closest "drive feel" to a normal gasser. Car is responsive, only slows a bit when foot is removed from the accelerator, etc. It has the lowest level of regen which means you maintain your speed longer. At 40 mph, it will take you just over 2 blocks to slow down to "idle" speed.
B mode can be looked at as "2nd gear" in a gasser. Regen is stronger and you will feel a "sluggishness" (which isn't really possible in an EV BTW...) or heaviness when driving. B mode will take you to idle speed in just over a block.
In both D and B, you must engage E Pedal or friction braking to come to a full stop.
Efficiency
EVERYONE has an idea of what efficiency means and how to achieve it but only a handful do so why is that? First off, regen is NOT your friend.
Regen is like that credit card in your pocket. It is very handy and convenient when you need it but as we all know, too much reliance on credit will get you in trouble. Regen is the same. Yes it puts some of that charge back into the battery but at the expense of velocity; velocity that will use more energy than regened to recover. IOW, its a no win scenario. The house always wins and that is due to gravity. Gravity takes from the charge coming from the battery and takes from regen going to the battery. Of course, manual friction braking should never be used unless absolutely necessary.
Now that we know what not to do, what do we do? Maintain velocity! After all you didn't get your car to park, you got it to go, so whatever it takes to go is your goal.
Negotiating Traffic
Above we talked about the different drive modes and how quickly they can slow you down. ALL of them would be just fine (actually not totally true and we will get to that) if you were the only car on the road. Well, that isn't going to happen so our efficiency goals are challenging in that constant changes in traffic conditions means constantly reevaluating the best drive mode.
When I brought my 2018 home in February 2018, I was an E Pedal fanatic. It was awesome especially in the stop and go traffic I dealt with daily on I-5 but soon quickly realized that the high regen made driving efficiently difficult without a very high level of concentration to my driving. At the time when I was doing daily phone conferences for work, etc. that was simply too hard for me to do. It was then that I decided to make a goal of driving an entire month w/o touching the brake pedal. The only real way to do that was manipulating regen to match the flow of traffic. I haven't accomplished that goal yet and July 2022 is out of the running but I did make it to the 20th one month so I am confident it will happen!
Anticipation
Expanding my "empty road" comment. Even without traffic controls or traffic, drive mode still matters and the biggest reason is its difficult to maintain a steady flow of power without actually thinking about it. Now, we all know its easy to do for a bit because we have all done it. But try doing that for an hour or even 10 minutes. Its tough! So for most of my driving, I am in D mode (ECO is ALWAYS on simply because there is no good reason to turn it off) because its the lowest level of regen and so those tiny slips of the foot means just a small regen hit instead of the very large one E Pedal provides.
Cruise Control
Cruise control is a way of maintaining pace with traffic. You can bump your speed up or down in one mph increments as needed. So its a convenience thing but its not very efficient. When the car slows due to small slopes in the road, the car will slow ever so slightly until it gets below its setpoint then overly accelerate to return to the set speed. IOW, its not very smooth. Unlike ourselves who can feel very small changes in velocity and increase power slightly to compensate, the car cannot. ACC is the same times 10.
Now, I have used CC a few times especially when I was in the middle of something like a call or whatever during very light traffic but I tend to avoid it for the most part. I live in an area where traffic flow is not consistent aggravated by complete disregard for the "stay right except to pass" law. So its a constant changing of speeds.
Scenarios
Remember the final takeaway YMMV and that applies to everything here. This includes what I am about to explain because I can only give you my experiences based on my local driving conditions which will be different than yours.
A typical drive on the streets, I am doing 40 mph, I see the light 4 blocks ahead turn red, I know its weight controlled and there will be about 6-10 cars in front of me so what do I do?
I immediately shift to N because it maintains the most speed and requires least amount of work so yeah, I am lazy but in random uncontrolled observations, it also seems to get me higher numbers so... Two blocks away, light turns green. I remain in N now going 35 mph. My hope is that the traffic will clear the light and I will pass thru the light at 25-30 mph using no regen at all shifting back to D. During this time, my surrounding aura is happy, everyone is happy. Life is good.
Same scenario above but this time its a major intersection during a busy time of the day which means a longer light cycle which means no chance of maintaining most of my velocity. Light turns red, I am 4 blocks away, I immediately reduce acceleration to maybe one bar slowing to 25 mph then shift to N. Aura is crashing! People around me are in a championship race to see who wins the "I spent the most time stationary at a stoplight" contest. Cars start zipping around me only to slam on their brakes to stop behind a line of cars still sitting at the red light. I now have just under a block to go to get in line at the light and it turns green, I shift back to D or sometimes B if the line of cars is long enough but eventually ending up in D. My goal is to have the intersection clear as I roll up at very low speeds generally under 10 MPH but that only happens about half the time so E Pedal is engaged if a full stop is required. Aura starts to climb. My fellow drivers are piling up stationary seconds at the light; all is good.
Big Hills
Being on the coast means everything runs downhill to the water. Since Olympia sits at the southern apex of Puget Sound and traffic flows around its eastern shore, I am facing major slopes in 3 different directions. Now, most of this is all about knowing the area but when coming to a big hill, regen is unavoidable simply so how to take the greatest advantage?
My process is actually probably not the best way as I tend to slow down all the way to the "maximum" legal speed limit which again affects the color of the local aura in a bad way, shifting to N which allows a quicker acceleration back to illegality then bounce from D to B to N as needed. The big current hits from doing this is not a good thing for the battery as it will last longer. Realize you are pumping power equal to DC charging speeds albeit for shorter periods of time. There are a few hills that have major arterial intersections at the bottom so traffic slows way down. In those cases, its generally less N and trying to stay in D so regen is lighter.
The Choice Is Yours
All this may seem unnecessarily complicated and it is otherwise there would be no challenge. The next issue to consider is will all that shifting wear out the tranny? Well, no tranny so no tranny to wear out. But there is a drive shaft to the front wheels but that is NEVER disconnected even when in neutral so wearing it out? Not too likely.
Now the key takeaway here is there is no single process that works if you are trying to maximize your efficiency. Conditions are constantly changing and each drive mode is designed to fit a very specific role. The other key takeaway is that this is what works for me. You may decide to stay in a drive mode and simply control power flow to minimize regen. That does work but takes a lot of concentration, more concentration then I have. Others may find it easy to maintain that steady foot so its really all about doing what works best for you.
Finally, I hesitate to present these numbers simply because there are too many variables to consider. I am a power miser during Winter, toggling defrost as needed, chilling ALL the time (but still comfortable) so my efficiency is higher in Winter than most because of me, not the car. But my 2018 I had a LT average 4.72 miles/kwh over 25,185 miles. Now my Plus is a bit of a different story as the extra range simply put my mindset into a situation where I felt like saving range on the freeway was no longer a thing so I became a criminal exceeding the speed limits by a "gross misdemeanor" margin quite frequently; something that VERY rarely happened in my previous four LEAFs.
Naturally that caused a drop in efficiency and at 35,000 miles on the Plus, I am at 4.48 miles/kwh but have exceeded 5 miles/kwh two months in a row and expect no different for July despite the HUGE increase in A/C use.
FYI; I admit to a bit of tongue in cheek in describing the scenarios above especially the "racing to red" stuff. But one thing I have noticed is that a lot more gassers are doing the slow roll from light to light like me. Really started noticing it a few months ago. I wonder why?
