What's most efficient. Drive in D or drive in B?

[Skryll]

I thought I’d weigh in with some real world numbers. I have a very consistent commute, which includes some surface streets, some highway, and one big hill in the middle. I’ve done the commute now a handful of times using the regen settings of B and D to record and compare the miles per kWh efficiency of each setting. I tried to make it as close to an apples-to-apples comparison as possible (same climate control settings, avg MPH, etc.).

In D mode:

4.4 M/kWh
24 mph avg

In B mode:

5.0 M/kWh
24 mph avg

For my commute, at least, there’s a clear (13.6%) efficiency advantage to driving in full B regen mode. If applied over a fully charged 24kWh battery (though I don’t think we ever get to use all 24 kWh), driving in B mode would add 14+ miles to my total range.

Switch to B, you’ll like it

-JM

Thanks for making the experiment. I also feel that B should be the default driving mode. All the extra D with variable regen settings and also the eco modes are not really useful.

Michael

 

[cove3]

The problem with the test showing greater miles/kwh in B than in D is that it defies the law of conservation of energy. Not only are you recovering more of the energy of the cars momentum from regeneration than recovering it via coasting, you're recovering more. From a physics point of view, it's like a perpetual motion machine. Something doesn't square

Ron

 

[SaintTiki]

Brake pedal =\= brake pad activation. Brake pedal = braking system. Braking system = regen + brake pads. If braking demand < regen deceleration, no pads are used. If braking demand > regen deceleration or speed < ~10mph, pads kick in. If you pay close attention, you can feel the difference between regen slowing you down or the pads slowing you down. When the pads kick in, the brake pedal feels more sensitive then when on regen only. This applies to all modes.

My hypothesis on why people get better efficiency in B mode is that they actively try to not use the brake pedal, meaning they plan their driving so they can slow using only regen until brake pedal is necessary at slow speed. Ideally, pads never kick in. If you drive in D mode and don't plan as well because you don't have that predictable decel, you are likely to end up too fast to slow down on regen alone and so the pads must kick in to help, wasting some energy. Also, if the car detects a rapid application of brake pad, like of a light turns yellow and you barely can't make it, then it automatically brings the pads into the equation as an "emergency stop" safety mechanism.

I hate B mode and D2/3 because I don't want my brake lights lighting up all the time just because I let off the accelerator. I only use them when I know I'll be in stop and go traffic or approaching a stop. Even then, I usually just apply brakes slowly and get the same amount of regen with the brake pedal.

 

[cove3]

1. It's my opinion brake pads are never engaged except during panic emergency stops. During normal braking in D, the needle never goes into the green more than it does in B, so there's no loss of energy from brake pads hitting metal

2. To make a fair comparison, while in D you have to anticipate and coast a lot, using the regen brake only for the last 10%. If you do this, I can't believe you won't get a higher m/kwh in D than you will in B. How material it is depends on what % of energy recuperation achieves

Ron

 

[NeilBlanchard]

Driving in B mode is how race cars are driven - and race cars are fun, but they are not efficient.

 

[user 241]

How to effectively use the modes provided in the e-Golf from my user experience.

I myself having switched from a manual transmission Golf found the transition to the e-Golf super smooth. My approach to the D, D1-D3 and B modes is exactly the same as with DOWN SHIFTING a manual transmission. Now pro or con's of downshifting a manual aside , this is only my point of view not the gospel. Take a penny, give a penny.

I would always coast down hill for the rollercoaster/alpine slide effect and tap the break slowly as needed or downshift approaching a full stop as my rmp/speed came into range. Depended on the road conditions, my mood and traffic flow.

Now for the beauty of the regen modes.
If the incline isn't steep, I put it in D1 and adjust it proactively if I want to go slower (increase up to D3) or coast to gain more momentum (put in D) to carry me over the next small hill while keeping under the speed limit.
Approaching a stop light/ sign or object, I cycle the D modes in measured increments then put it in B mode for increased reduction before I softly put foot to break peddle. I have observed a mile or two miles increased on each of the hills I travel on using this method.

I have been to Vermont with my old ICE and those steep downhill rides would probably gain a good regen. It's a tempting trip in the e-Golf.

The longer you coast or break the more boost you get to the range that is available with the current charge. The efficiency of fuel usage is where the Drive modes Eco and Eco+ come into play which reduce the throttle response as well as the AC.