In upcoming State of Charge columns, electric vehicle owner and Canadian Green Car award organizer Michael Bettencourt will share tidbits of news and driving impressions from seat time in various plug-in, high-mileage and alternative fuel cars from a green car enthusiast’s perspective. Up first, he digs down into why BMW’s plug-in i3 may not be as efficient as possible, and provides some fuel-saving tips for all drivers.
Driving Notes: 2015 BMW i3
Max regeneration, efficiency tips (gas or electric) and missing neutral
One of the most noticeable driving traits of the futuristic BMW i3 is the aggressive regeneration as soon as you lift off the accelerator, which had my passenger’s head bobbing back and forth like I was a crazed student driver for my first 20 minutes driving BMW’s plug-in hatchback. But once you become used to what initially feels like continually driving in second gear, owners often profess a love of one-pedal driving, because the regen is strong enough to brake the car down to a full stop by simply lifting off the accelerator.
Even the brake lights come on if you lift off the throttle enough, and it doesn’t have to be a total lift – so yes, the brake lights can be on while you’re pushing only the accelerator.
But as I’ve learned in my Leaf, which has an Eco mode that also increases the regeneration levels significantly, to truly maximize how far one can travel on a charge, coasting in neutral is a better friend than heavy regeneration when it comes to maximizing efficiency and stretching one’s overall range.
Wait, but how can this be? If every Eco/Brake/EcoPlus mode offered on plug-in cars increases regeneration, and thus recaptures more braking energy, then it must give you more overall range when engaged, right? Well, not necessarily, because the extra retardation that comes with these modes must be “made up” by extra energy use when it’s time to get moving again.
The power recouped by regeneration is rarely (if ever) as substantial as that of the kinetic energy already propelling the car forward. Thus strong or extra regen is great when you’re coming up to a fresh red light or stopped traffic, or whenever there’s no way to avoid coming to a complete or near complete stop.
But just as it is in a regular gas car, keeping your eyes up and timing those lights by lifting off the throttle earlier so you never have to stop would be much more efficient. Unless you’re talking about long or steep mountain descents where you’d have to brake anyway, it would be more efficient to coast in neutral in any EV down a long hill and build up some momentum to help travel as far down the road or up the next hill as possible, without using further fuel.
This becomes an issue with the i3 is because you can’t select neutral while on the move, likely to protect the unique twistable gear selector from being shifted to nearby Park or Reverse. There is still a Neutral offered, available for drive-through car washes and such, but accessible only when stopped. Instead, the i3’s accelerator is supposed to have a “distinct ‘neutral’ position,” a middle point in which neither regeneration nor acceleration occurs. But after another recent but short drive of the i3, finding that position was difficult, if not near impossible, as owners have reported online as well.