Consumer Reports "Review"

[Don]

Regenerative braking is fantastic at recovering energy when you actually want to slow down, but it's far from 100% efficient, so "B" mode can be wasteful if you're needlessly toggling between accelerating and braking.

I find the B mode delightful AND efficient. With just a little practice, you simply position your foot on the accelerator for the level of acceleration, coasting (in the middle), or regen-braking you want. Because B gives you full acceleration AND full regeneration, it's a beautiful simple ride with one foot and the occassional tap on the brake for full stops. Love it!

+1 - It's the only mode I ever use. I really like it because it closely mimics driving an ICE with a standard transmission and prior to this car, that's all I've ever owned. Lift your foot off the 'gas' at any time and you and you have maximum engine braking . . . . you don't even have to downshift. I seldom ever touch the brake pedal until I'm down under 10 MPH . . . . I use regenerative braking for everything else - You quickly learn when to release the throttle so that your speed is down to what you need for turns and stops. Works GREAT!!

Personally, I find most people who are 'needlessly toggling between accelerating and braking' grew up driving cars with automatic transmissions and they usually are left foot brakers which is something us manual trans guys never got in the habit of . . . . watching their brakelights flickering off and on several times per mile when I haven't touched mine is a constant source of 'entertainment' for me - I can only imagine how often they must replace brakepads and tail light bulbs!

If you can drive an ICE rated at 30 mpg and constantly get better mileage than that, you'll be just fine driving an EV in full regen brake mode 100% of the time . . . . but wasteful habits in other cars CAN transfer over to EV's as you so correctly point out

Don

 

[tonymil]

Don,

I too come from a standard transmission background and I've taken a different approach. I generally use "e" mode and switch to "d" only when I'm seriously lagging behind or when I'm merging into faster traffic or climbing a steep hill. I get out of "d" mode and back to "e" as soon as I don't need the hard acceleration. I shift to "b" mode whenever I need to decelerate, whether traffic is just slowing down or I'm coming to a stop. Sometimes I switch to "b" mode too soon and decelerate too fast but I'm getting better at timing it based on conditions. When I'm sitting at a red light I switch to neutral. All this shifting hopefully is maximizing my range, but it also gives me a feeling of control over the car similar to driving a standard transmission.

 

[jennrod12]

I come from an automatic transmission background, but no left-footed driving.

I started out always driving the i in E mode, but during commute times I hit a lot of "slow and go" traffic (not "stop and go") and the E was slowing me down too much so I tried switching to D and really like it! With E or B, I find I need to balance my foot on the go-pedal at "just the right spot" to slow down the correct amount, which is difficult. In D it is very natural to take the foot off the go-pedal and slow down at a reasonable rate. When driving in D, it's also easier to switch to N for long, gentle, cross-traffic-free downgrades, which I sometimes encounter on my commute.

Driving mostly in D, I do use the brake pedal more, but I press it very gently to maximize it's regen ability before moving onto the mechanical brake. When I need to stop, I'll often switch into E first, sometimes B if I need to slow down faster or stop sooner. Switching to E also helps remind me to accelerate more slowly when starting off from the stop, too.

Jenn

 

[JoeS]

Well, I cooled off a bit and made the following submission as a review of this article in Consumer Reports:

As a long-time (>50-years) Consumer Reports subscriber and i-MiEV owner with over 4000 miles on the car, I am appalled at the shallowness and personal bias exhibited in this preliminary Mitsubishi i-MiEV overview, perhaps by someone more used to driving SUVs and not small (NOT tiny) fuel-efficient vehicles. The inordinate attention to "range anxiety" reflects the lack of experience and absence of basic math skills on the part of the reviewer and drivers, who appear to have been thrown to the wolves with no introductory briefings.

First off, the user must understand that this is a limited-range vehicle, whose overwhelming attribute is that of zero emissions. Since according to the Bureau of Transportation Statistics the average US driver covers 29 miles daily, the i-MiEV certainly fulfills the driving needs of the majority of Americans. It's range is very well-defined, with a prominent "Range Remaining" dashboard display coupled with a 'fuel' gauge for further reassurance. It is inexcusable for anyone to undertake a trip in this vehicle without knowing how far they expect to travel (after all, this is the 21st century with GoogleMaps and GPS and SmartPhones) - if the distance is marginal relative to Range Remaining, you simply DON'T DO IT and either fully-charge the car to get your desired range or else take a different car. DUH! This vehicle is unsuitable as the 'only' vehicle for most families; however, in many cases (mine included), it has become the PRIMARY car in the family, with the internal-combustion-engined car relegated to use for only long trips. It is presumed (and a prerequisite for purchase) that the owner has access to Level 1 (120vac) or (preferably) Level 2 (240v) outlets, which easily yields daily driving distances well over 100 miles, with opportunity-charging during the day. The Range Remaining display has proven to have a more refined algorithm than the similar display in the Leaf, yielding numbers that can be relied upon given consistent driver operation and terrain. Knowledgeable Electric Vehicle drivers DO NOT have 'Range Anxiety' (a term General Motors tried to trademark), because we know PRECISELY what our limits are (unlike the internal-combustion-engine commuter late for work and running on empty).

Please note that this is only the second modern mass-produced affordable EV to be available in the US, with a pricetag notably less than the opulent and larger Nissan Leaf. The attributes of the i-MiEV that were either not mentioned or glossed-over: small exterior yet a very spacious and comfortable (yes, VERY comfortable! - I disagree with your reviewer) interior, especially with the rear seats folded down yielding a flat floor with more usable capacity than the Leaf. Its tight turning radius which facilitates very easy parking, a high seating position with plenty of headroom and easy ingress/exit, good all-round visibility, silent operation, brisk acceleration providing effortless Interstate merging even with full load, and a top speed exceeding 80mph are all attributes well worth mentioning. Handling is certainly more than adequate for an urban vehicle, and it has a modern braking system and active stability control and a host of safety features. Why wasn't all this mentioned?

Finally, the ridiculously low operating costs and convenience of home 'refueling' relative to an internal-combusion-engine vehicle should perhaps merit further emphasis. My own long-term wall-to-wheels normal-use non-hypermiling consumption average of 4.3miles/kWhr leads me to suspect your drivers are inconsiderate energy-wasting leadfoots incapable of keeping the Power Gauge in the Green Zone and who probably shunned the i-MiEV's 'Eco' driving mode which enhances range-stretching energy conservation.

Let me just say that my own experience with cars that I bought that had been reviewed by CR is that their perspectives and mine are very different.

 

[Vike]

Don,

I too come from a standard transmission background and I've taken a different approach. I generally use "e" mode and switch to "d" only when I'm seriously lagging behind or when I'm merging into faster traffic or climbing a steep hill. I get out of "d" mode and back to "e" as soon as I don't need the hard acceleration. I shift to "b" mode whenever I need to decelerate, whether traffic is just slowing down or I'm coming to a stop. Sometimes I switch to "b" mode too soon and decelerate too fast but I'm getting better at timing it based on conditions. When I'm sitting at a red light I switch to neutral. All this shifting hopefully is maximizing my range, but it also gives me a feeling of control over the car similar to driving a standard transmission.

I really appreciate all the descriptions provided here of different approaches to using the drive mode selector to best effect. I think it's a testament to the flexibility and utility of this powerful feature.

tonymil, your driving style comes very close to the technique I gradually adopted during an extended test drive (slow afternoon and I think my salesman was glad for an excuse to stay out for a while). I haven't driven a stick in years, but my first two cars were manuals, and I really enjoyed driving them, so that may be a factor in how quickly I started to use the drive mode selector as a kind of shifter. I found "e" much more broadly useful than I originally expected, but "d" made freeway merging more straightforward, and was useful a few times as the light turned green and there was an opportunity to get around a slow moving vehicle. We did a longish downhill stretch at one point and "b" was great for that, but also for approaching stops generally. I find the ability to select the "coasting" re-gen level through the drive mode selector a real plus, something I've often wanted to have in our Prius (and something I've occasionally had to explain to fellow Prius drivers is not provided by the engine braking "B" position on the Prius shifter, which is useful only on downhills and provides no addl. re-gen at all).

The only point I was trying to make about the reviewer's comments about "B" mode was that it's a great oversimplification to suggest that this mode provided the maximum range. If you've got a good stretch where it makes sense to coast, it's most efficient to do so in "D" (never been a big fan of moving along in "N", which I feel sacrifices too much control), which will allow the car to maintain momentum with the least re-gen drag. Shifting to "e" or "b" makes sense at the point that you actually want to slow down, but staying in "b" all the time would, I think, require very fine application of accelerator pressure to optimize the level of re-gen vs. coasting, something I think might more easily be achieved by changing drive mode. But that's just for me - what I love about the drive mode selector is that it allows the driver such finely selectable control over regen. With such a great tool at hand, I say to each their own.

 

[Don]

The only point I was trying to make about the reviewer's comments about "B" mode was that it's a great oversimplification to suggest that this mode provided the maximum range. If you've got a good stretch where it makes sense to coast, it's most efficient to do so in "D" . . . .

I think that once the driver is properly trained to use it, the B mode does provide the best range - It regen's even more than the Eco mode, yet it provides all the oomph that the D mode does for those times you need it

On page 4 of the Owners Handbook they have a table of things which they list as 'Range Reducing' or 'Range Extending' - The usual things you'd guess are 'Reducing' such as heater or A/C useage, high acceleration rates and high speeds, hilly terrain or rough roads are listed there. Conversely, not using heat or A/C, accelerating more slowly and keeping speeds down, flat terrain and such are all 'Range Extending' virtues. At the bottom of the page under 'Reducing' they list driving in D-mode and for Range Extending, they list Eco or B mode

'Coasting' dowhill in B mode doesn't take any more energy than doing so in D . . . . the needle sits on the line between the blue regen area and the green economy area just like it does if you were in D, with the added plus that if the guy in front of you hits his brakes, you just lift your foot to hit regen instead of your brake pedal . . . . and get a free charge in the process

I agree it's not right for everybody - Not everyone is interesting in thinking ahead about getting maximum range all the time as they drive and the B mode does pretty much require that. I find that I can easily drive 50 or 60 miles even using the A/C most of the time and still get home with 15 or 20 miles showing on the RR dial, so I definitely don't think the B mode is 'costing' me anything . . . .

Don

 

[Vike]

'Coasting' dowhill in B mode doesn't take any more energy than doing so in D . . . . the needle sits on the line between the blue regen area and the green economy area just like it does if you were in D, with the added plus that if the guy in front of you hits his brakes, you just lift your foot to hit regen instead of your brake pedal . . . . and get a free charge in the process
Don

Don, I think that describes exactly the very fine application of accelerator pressure I was talking about. You're talking about "coasting" in "b" but with your foot on the accelerator to, well, effectively back off the regen to avoid losing too much speed. A similar result could be achieved by shifting to "e" or "d", depending on how much re-gen braking you wanted.

What I found interesting about driving the i was the way you could choose different ways of achieving the same re-gen/coasting balance, whether by lightly braking while in "D" or "E" to get more re-gen, or lightly accelerating in "B" to reduce the re-gen. You can get as involved as you like with all this using whatever tools are most convenient, depending on driver preference.

There's a point I've been trying to make that I'm going to try one more time to phrase a little differently. My concern when I read some comments is that regenerative braking is perceived or characterized as a magical recharging feature providing free energy. That's not it at all. Regenerative braking converts momentum into stored electrical energy, and as with all conversions, some loss is entailed as you're charging, and some as you're drawing energy to re-accelerate. Net/net, if you let the car coast to a stop, you will have used less total energy than if you drove under power and then decelerated to the same spot using "b" mode. I'm not sure everybody gets that.

Put another way, all braking is bad for range, but braking is something we have to do in normal traffic, and some braking is worse. Using regenerative braking, which loses a little energy in conversion, is greatly preferable to mechanical friction braking, which wastes all the energy. So, compared to not braking at all, re-gen braking never adds range, but it reduces it a lot less.

 

[fjpod]

Others have said it, but I'll try to say it differently...the best way to achieve good mileage is to not accelerate any more than you have to, to roll to a stop without braking of any kind. If you have to brake the car, you accelerated too much and wasted power. Its better not to use the power in the first place, than to try to gt it back later by regenerating.

Now in the real world, we often have to stop unexpectedly, or we have to keep up with traffic, or to simply just get to where we are going.

Eco mode is good in the sense it keeps you from being too fast on the accelerator pedal, but if you let it slow you down unnecessarily, it is bad.

 

[MLucas]

Two comments on this thread. I think all of these new EV cars will eventually get a lot of backlash and these articles that will float to the general consciousness won't help (aka spin). This car is about change and human beings in general are not comfortable with change. Remember Jimmy Carter put up the solar panels on the White House pool to only have Ronald Regan take them down.

EV's represent the consumer taking control of their own energy management instead of letting an energy company like BP or Shell do it for them and convenience is costly. We can now choose where to get the power for our vehicles (local utilities, solar, wind, etc.) and how much of that power we want to use in our driving. Our I MiEVs give us the power to drive aggressively or conservatively right in the mode selector. That is true power.

As far as my driving style, I like to drive in Eco and brake using B. I get the best range while driving and get the most regen available. When I coast in Eco the needle doesn't bottom out like it does in B. Whether I'm driving auto or manual trans ICE, I've always coasted to stops and limited my use of breaks. I'm quite used to this method of breaking. Last Friday, when I picked up the car I was getting about 91km range on a full charge, yesterday after a full charge I'm up to 137km range. Something must be working right!