Select N while waiting at traffic lights?

In my previous life with an automatic ICE I used to slip the gear out of Drive while waiting as I felt it reduced wear on the automatic clutch. What about in the i3? Is there any benefit to be had from slipping the gear change into N while waiting and putting on the handbrake?

I always use the handbrake if stopped for more than a few seconds: my motivation is partly to prevent the need for the motor to hold the vehicle on a slope, which would use a little power. I see no benefit whatever of putting it in neutral, only a disbenefit of a delayed take-off when the lights change.

I always use the handbrake if stopped for more than a few seconds: my motivation is partly to prevent the need for the motor to hold the vehicle on a slope, which would use a little power.

Click to expand...

The amount of power it uses will not depend on whether the handbrake is on or off. However, it's better to use the handbrake when stopped if only to avoid your brake lights dazzling the guy behind. Don't forget that - with your foot off the accelerator - the car doesn't roll back when in Drive on an upward slope, and doesn't roll forward when in Reverse on a downhill slope.

I see no benefit whatever of putting it in neutral, only a disbenefit of a delayed take-off when the lights change.

Click to expand...

Quite so, and it avoids the brake light flash, too. But if you really want to save a few yards of range :lol: , Neutral or Park is better when stopped. And Park avoids the need to use the handbrake (the car is really held locked), and saves another couple of feet of range by avoiding actuating the handbrake. But the brake lights will flash when you need to move off again.

FrancisJeffries said:

I always use the handbrake if stopped for more than a few seconds: my motivation is partly to prevent the need for the motor to hold the vehicle on a slope, which would use a little power.

Click to expand...

The amount of power it uses will not depend on whether the handbrake is on or off.

Click to expand...

Not so

Page68-69 of the owners handbook:

Hold Function.
Principle.
The system holds the vehicle at a standstill automatically with a gear engaged. Rolling opposite to the direction of travel is prevented.

Click to expand...

and:

Information
To reduce energy consumption with the hold function active, apply the parking brake or engage selector lever position P.

Click to expand...

We are straining nats here people. How much electricity are we talking about here with the brakes applied as opposed to engaging the parking brake and the brake lights in the followers eyes, give me a break.

mindmachine said:

We are straining nats here people. How much electricity are we talking about here with the brakes applied as opposed to engaging the parking brake and the brake lights in the followers eyes, give me a break.

Click to expand...

No-one is telling you to do it, mindmachine, but if BMW put it in the manual they wouldn't have suggested it would save energy consumption if it didn't. We are not talking about brakes applied, we are talking about resting on the engine which will prevent you from rolling backwards, consuming power to do so. I suspect the only real benefit is if you are stopped on a steep slope and you are going to be there for a while, or slow stop-start traffic up hill.

There is no wear when the car is sitting since the motor is truly stopped. They do run a little current through it to perform the hold function, so since the parking brake effectively shuts that off, that is the minor difference.

jadnashuanh said:

There is no wear when the car is sitting since the motor is truly stopped. They do run a little current through it to perform the hold function, so since the parking brake effectively shuts that off, that is the minor difference.

Click to expand...

As a soon to be REx owner, this is helpful advice. FWiW, the advice from the UK's Institute of Advanced Motorists is the ICE automatic car owners should leave the car in 'D' and not 'N' at junctions, traffic lights etc. The gearbox wear when stopped in 'D' is minimal compared to the wear incurred when selecting lever options. The engine power at idle is absorbed by the torque converter. This advice worked well for me.

Not sure if the following works in an i3 but it's a blast in a Nissan Leaf:

At red traffic lights, select N and fully depress accelerator. When lights change to green, rapidly shift into D and enjoy instantaneous, cheek-wobbling acceleration!

Looking forward to trying this in the i3

I'm pretty sure the I3 will not let you engage D unless the brake is pressed, don't know what would happen if you left foot brake with the right foot on the throttle

I33t said:

mindmachine said:

We are straining nats here people. How much electricity are we talking about here with the brakes applied as opposed to engaging the parking brake and the brake lights in the followers eyes, give me a break.

Click to expand...

No-one is telling you to do it, mindmachine, but if BMW put it in the manual they wouldn't have suggested it would save energy consumption if it didn't. We are not talking about brakes applied, we are talking about resting on the engine which will prevent you from rolling backwards, consuming power to do so. I suspect the only real benefit is if you are stopped on a steep slope and you are going to be there for a while, or slow stop-start traffic up hill.

Click to expand...

I read the manual too and it says "for long periods of time" still say you are straining nats here like I said before.

I agree if you are stopped waiting for a train or the traffic is stalled do to a problem, sure I would engage the parking brake too, but normal stop and go traffic at a stop light, 30 to 60 seconds with my foot on the brake would be it for me. And as far as the brake lights dazzling the driver behind me, that is what brake lights are for, to warn someone that you are not moving.

noodle said:

Not sure if the following works in an i3 but it's a blast in a Nissan Leaf:

At red traffic lights, select N and fully depress accelerator. When lights change to green, rapidly shift into D and enjoy instantaneous, cheek-wobbling acceleration!

Looking forward to trying this in the i3

Click to expand...

In the i3 just leave it in D with the handbrake on. When the lights go green stamp on the pedal and off you go. No need to release the handbrake as its automatic. No need for neutral as theres no ICE spinning.

I didnt need the manual to realise the car was holding itself from rolling back using the motor and thought... probably best to stick the handbrake on. If you do think about it... how many newtons of force do you think it takes to hold 1200+ kg on a slope. Where is that force coming from? The battery.

I got told off by the car the other day... Id left it in ready to drive In N whilst picking up my son. Handbrake on. Got out to help him load a PC into the boot. When I got back in the car the display said "always leave the car in P when parked on a slope to prevent it rolling away".

Almost all ICE cars sold in the USA are automatics, and even if they aren't, have people holding the brake while stopped at a light. Now, yes, I suppose those bulbs take a bit of power, but the hill hold function really only works if gravity would push you back from the direction the transmission is trying to drive you. The only time I've been in an accident is if the idiots behind me didn't stop when I did, so I could care less about saving a watt or two...the more noticeable the car is, the better! If it's level, you may not need to use the brakes, but any slight decline, the car will creep from gravity if you don't. I doubt you're talking much. To see power flow, go to that screen on the idrive menus. I don't think it would be a great idea to go into park, either...running that pawl in and out probably takes as much power as the brake lights, and then you have the switch and the actual locking mechanism to think about.

Again, with an ICE automatic, you've got some drag from the rotating engine trying to drive the transmission, but you have none of that in the EV - stopped, the motor is not turning, period.

I vote for D and handbrake, though you have to careful not to rest your foot on the accelerator.

As the originator of this question I have to say I love this forum. Who would have thought that such a mundane question (posed originally by my nervous wife driving my baby) would generate so much useful advice? In fact she told me she has already worked out that if she leaves it in Drive and applies the handbrake she can beat anybody away from the lights without even having to release the handbrake. While I am slowly increasing my efficiency (best 86% so far) I noticed her last journey was 12%!!

whistleworm said:

my nervous wife ...I noticed her last journey was 12%!!

Click to expand...

Ermm. No comment!

Short errand runs are probably the worst since you're rewarming the interior and batteries multiple times, especially if it is really cold, and you're in the store or stop for a bit.

Since I mostly use my car for errands around town and I charge every night I have taken to leaving the climate control running when I lock the car. I don't know of it affects the battery pack, but it is nice not to come back to a hot car. It was in the low 80's for the last few days and we expect more of the same. I just tick the option for Comfort Climate Control on shutdown.

My gut feeling, especially with a/c, it's probably not a major hit to keep the car cool if you're not going to be out of it for all that long. The bigger hit is on a REx in the cold...resistance heating is your only source, and that is one watt out of the battery, one watt into the car. The a/c could be 3-4x more efficient at moving heat around (as could a heat pump, if you had one). Look at it this way...in the summer, you might be trying to drop the interior temp 10-20 degrees, but in the winter, you could be trying to warm it 50-70 degrees...you'll use more energy doing that in the winter and your batteries won't produce (release) as much.