Mitsubishi i-MiEV Part I: Driving

Imievgarage
In an earlier post, photographer Ian Merritt discussed his experience as the first staffer to take home the Japanese version of Mitsubishi's i-MiEV battery-electric car. In the following two-parter, I'll detail the driving experience and some of the drawbacks of what is essentially a silent car.

Our car had keyless access and keyless start like a lot of cars do nowadays. With the keyfob in your pocket, you can unlock the doors by pushing a button on the driver's door, and then start the car by turning a knob where the ignition key would be. Notwithstanding the fact that our car was right-hand drive, it was like a normal car in most ways. When you first turn it on, you hear some buzzing from the back, which is the electric power-brake assist preparing for the next stop. The sound then goes away and comes back only after you hit the brakes a couple of times. You don't hear it at all once you're on the move.

Imieivprofile
The i-MiEV (pronounced EYE-meev, according to Mitsubishi) has impressive get-up-and-go even with four occupants, as is the norm for electric cars. It doesn't make for lightning-fast sprints to 60 mph, but it's quite satisfying in urban and suburban settings. The transmission has the familiar PRND settings, plus Eco and B modes. Drive is the most like a normal car in that it lets you coast along when you lift off the accelerator. Eco gives you more engine braking (or motor/generator braking to be exact). The B setting, which we've seen on some hybrids, gives you even more engine braking. Coasting down a hill, I switched from Drive to Eco to B and felt the car decelerate faster with each change. With the greater braking comes more battery regeneration, as indicated on the charge gauge. This type of braking will boost the electric vehicle’s range.

Imieivshifter
With its increased regeneration, B turned out to be the most efficient mode. By controlling the car's acceleration and deceleration with the accelerator pedal, I maximized regeneration and made very little use of the brakes. Unlike hybrids, the i-MiEV's brakes don't regenerate energy. They're just normal brakes, and as such, they operate and feel better than brakes on most hybrid cars. But they actually rob you of efficiency by turning your inertia into heat in the brake pads rather than electricity in the generator. The best-case scenario is that you use them as little as possible, and the B setting does this best.

So what's Eco mode? It makes the accelerator pedal — there’s no gas, after all — less sensitive and provides more regeneration than Drive but not as much as B. Here's my problem with it: It doesn't just change the nature of the accelerator response; it limits your power. When you floor the pedal, the i-MiEV scoots from zero to 45 mph in about 7 seconds when in Drive and B. It takes 9 seconds when in Eco. Whether it's in an electric, gas, diesel or any other kind of car, an economy mode should always give you full power when the pedal is floored. It's the only safe approach.

Imievunder
Overall, the i-MiEV was a fun experience. Its shortcomings — top-heaviness, susceptibility to crosswinds and prodigious wind noise at highway speed— are a byproduct of the car, not its electric nature. (The "i" has been sold overseas for about five years with a three-cylinder gas engine.) Comparisons to the Smart ForTwo are natural, and we noticed similar problems with that car — plus a good many others.

That's not to say the electric aspect didn't have its shortcomings. I'll address those in Part II.

Comments 

Wow, this is crazy. I never knew the transmission of electric vehicles was different from normal cars and so complex, I just assumed it would be D,R,N etc. One time I got confused already in my normal car, I forgot if I was supposed to be in D1 or D2?! I would need a manual taped to the windshield to drive this electric car.

Dan

Shop-

Electric vehicles don't have transmissions, which makes them pretty darn simple.

Tony

What funny is that BMWs have electronic transmission shifters on regular cars but this electric car has "shifter-like" shifter

Dan,

There is an Eco and a B gear... I now see its the same as regular car, N, D etc except the Eco and B part...

"Unlike hybrids, the i-MiEV's brakes don't regenerate energy. They're just normal brakes, and as such, they operate and feel better than brakes on most hybrid cars."

Hybrids have "just normal brakes" too. Trust me, I've have to pay to get mine replaced...

Regen is basically converting kinetic energy back into electrical potential through reverse operation of an electric motor. It might be that uprated power electronics and battery capacity of the i-MiEV allow it to do more of its braking using regen than a typical hybrid, with less of a noticeable transition to friction braking. But the parallel systems of regen and friction braking are functionally identical on EVs and hybrids.

Zack

The "B" mode is not meant to be used for normal driving - it is only for occasional use to simulate engine braking when the car is going down a steep hill - to avoid a runaway scenario with the coast happy EVs. Driving in "B" mode for extended periods will fry the drivetrain pronto. Please check with Mitsubishi to confirm. The brakes in hybrid cars don't "regenerate energy" as stated in this post. Regeneration of the battery is a process that uses only the on board electric motor(s). The moment you take your foot off the accel pedal to slow down, a drive motor switches into generator mode, with the kinetic energy of the moving car spinning the motor to send power back into the batteries. Because of the drag created by the regeneration process the brakes are much more responsive and may have a "grabby" feel to them that some hybrid drivers complain about. But as Sierra stated above, the brakes still function as normal brakes with or without regeneration taking place.

I'll take a second to elaborate a bit and correct some of the corrections above. Please bear in mind that in the interest of brevity and the accessibility of our content, we must simplify and sometimes oversimplify in our original posts.

Technically and figuratively, Shop is correct that the i-MiEV does have a transmission. It's a simple gear-reduction system, which not all EVs have. What it doesn't have is different "speeds." Ultimately, in the sense that the user interface -- what normal people interact with every time they drive a car -- is very much like a transmission, in the casual sense, it's a transmission.

It's the lack of speeds that contradict the assertion that driving in B mode could damage anything. You wouldn't want to drive a normal car at highway speeds in a Low mode or low gear because, at minimum, it would waste fuel. There's nothing in the i-MiEV that will fry from driving in B at any speed the car can attain. If my word isn't enough, yes, Mitsubishi concurs. The main drawback to B mode involves traction on snow or the like, in which letting off the accelerator quickly can result in too much braking to the drive wheels. In these conditions, Drive is better.

Conventional hybrids use regenerative braking. In all of these systems, the drive motor doubles as a generator that recharges the battery when coasting/decelerating. The difference between these and the i-MiEV is that hybrids increase the regeneration and slow the car faster in response to stepping on the brake pedal. All vehicles have conventional brake pads or shoes, and in harder braking, the hybrid transitions from one to the other. (Technically, it simply combines friction braking with regen; it's not necessarily a one-for-the-other trade.)

In the i-MiEV, the brake pedal activates the pads and shoes, and that's it. Where hybrids attempt to continuously vary the amount of regen (and thus braking) based on brake-pedal position, the MiEV gives you three _rates_, each selectable via what most people would consider the transmission, with a degree that's continuously variable based on accelerator-pedal position. As stated in the post, any time you use the brakes, you're robbing regen, not triggering it as you do in a hybrid.

Thanks for the opportunity to elaborate and to everyone for joining the discussion!

ermatthe

game, set, match

lol

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