Or, “Which mode do I use?”
In September 2011 we wrote an article about the ECO drive mode on the LEAF. It has proven to be one of our most read articles. For the 2013 model year, Nissan has offered some changes to the system on the SV and SL trim levels. This article is an update of our previous article as the new B-mode did not exist on the 2011 or 2012 models. If you are unfamiliar with the basics of the ECO drive mode, we suggest that you start with our earlier article (found here), as this newer technology builds upon the previously existing technology. The 2013 S trim level does not offer the B-mode and will operate as before. We will dive a little deeper into the brake regeneration this time also. Near the end of this article, we will provide some casual test data to show the difference in operation among the various modes.
The Nissan LEAF now offers four distinct drive modes on its upper two trim levels – Drive, Drive ECO, B-mode, and B-mode with ECO (or as my wife calls it – Bahonkin’ ECO. Not really sure how she would spell it though). Let’s start with Drive mode.
Drive mode is engaged by moving the shift lever to the left and back one time. This is the equivalent of selecting Drive on a traditional automatic transmission on an internal combustion engine (ICE) vehicle. When in Drive position the accelerator pedal provides Nissan’s standard throttle responsiveness for acceleration. Lifting off of the throttle at speed provides mild regenerative braking. When you are accelerating, the electric motor turns the wheels. When you are decelerating the wheels turn the electric motor, which is now acting as a generator. Traditional friction brakes, be they disc or drum, turn kinetic energy into heat by creating friction. This heat is then dissipated into the air as wasted energy. An electric vehicles’ regenerative braking system captures some of that kinetic energy through the electric motor and sends it back into the battery as electricity.
The Drive ECO mode is engaged by placing the shift lever into the Drive position, and pressing the ECO button on the steering wheel. The dash indicator will now show D with ECO next to it. Pressing the ECO button does three things – first, it changes the responsiveness of the accelerator pedal by requiring the driver to press harder to achieve the same rate of acceleration; second, it provides slightly more brake regeneration than the Drive position; third, it slightly impacts the operation of the heater and air conditioner to improve energy usage. By doing all three of these things, range may be improved between five and ten percent according to Nissan.
B-mode is engaged by moving the shift lever to the left and back two times. The first movement will display D on the dash. The second movement will display B on the dash. B-mode provides more aggressive brake regeneration than either Drive or ECO. In Nissan’s words from the 2013 LEAF Owner’s Manual:
B-mode: Engages the regenerative braking system more aggressively on downhill slopes, and helps reduce brake use.
That seems to be a succinct and accurate description of B-mode. We would add that it is not limited to working only on downhill slopes. It also provides more aggressive braking in any driving condition.
Finally, B-mode and ECO may be engaged concurrently. Initially we thought that this would provide even more brake regeneration than B-mode alone, while also providing more resistance and slower responsiveness to the accelerator pedal. It turns out that brake regeneration is not enhanced over B-mode alone, but it does slow the responsiveness of the accelerator pedal, as it does in Drive.
Now for the non-scientific testing to validate the above statements.
We live near a parkway with a 55 mph speed limit and a short 50 foot elevation change over two tenths of a mile. We accelerated to 55 mph and coasted through the downhill portion of this elevation change. We did this three times for each of the four drive modes and averaged the results. This is what we found:
|Blue Regen Dots
|B-mode with ECO
So the real question now is how does this help you in your everyday driving? Our intent is that it will better help you select the proper mode at the proper time.
If your everyday driving consists of significant stop and go city traffic (or stop and go freeway traffic for that matter) you can maximize brake life and further reduce maintenance costs with ample use of B-mode. We have learned that B-mode’s brake function is strong, and that our initial driving using this mode almost always included having to accelerate to the stop sign or traffic signal as we slowed down before we expected to. This reminded us of our racing days and this phrase in particular – the throttle is not an on/off switch. When approaching a stop sign, or red light while using B-mode, rather than lifting your foot completely off of the accelerator pedal, try just lifting part way off. Eventually you will learn the art of accelerating and braking just with the accelerator in many situations.
When driving in hilly terrain, the B-mode can be used quite effectively to modulate downhill speed. As its regen mode is relatively aggressive, you may find yourself shifting between ECO and B-mode depending upon speed and incline, perhaps even using Drive mode with slight inclines.
As far as the difference between using Drive and ECO, it may come down to personal preference. We know many individuals that have experience in German vehicles that prefer the pedal feel when in ECO, as many German makes offer firm pedal resistance. Others prefer the lighter and quicker responsiveness in Drive mode. One thing to keep in mind is that the ECO mode does provide a significant amount of brake regen compared with Drive mode, based on our findings. Also, a quick reminder that while in ECO mode maximum acceleration is still available by fully depressing the accelerator pedal.
There is no right or wrong way to use any of these modes. What you want to sort out for yourself is which mode do you prefer in any given situation. There is no way that you can damage the car by using any of these drive modes. If the B-mode offers too much braking for your taste, try the ECO mode. If the ECO mode isn’t slowing you down as much as you would like, try the B-mode. In the end it comes down to being able to personalize your car for your driving style. With all of these modes to choose from, you can tailor your LEAF to the way you drive making for a more enjoyable ownership experience.