BMW i3 Range Extender: First Drive in the electric car without range anxiety

BMW expects the i3 ‘Range Extender’ to comfortably outsell the standard, purely electric version. The reason for this is simple: it can go almost twice the distance as the normal i3 and at the end it doesn’t have to stop to recharge its battery. If that sounds like a silver bullet for so-called ‘range anxiety’ that’s because it (almost) is.

ecomento spent some time with the BMW i3 Range Extender in the UK to bring you our first impressions of what may well become a decisive vehicle for electromobility.

How does it work?

In much the same way as Chevrolet’s Volt, which is to say that a small gasoline-powered combustion engine runs a generator to maintain the lithium-ion battery’s state of charge when it falls to about five percent. The range extender never directly drives the BMW i3’s wheels, so the car’s driving characteristics are only ever those of a pure electric car (namely instant, smooth acceleration), despite the fossil-fueled help it’s getting.

Given the car’s Environmental Protection Agency (EPA) range rating of 72 miles in electric mode, we’d expect the range extender to fire up after around 68 miles of zero-emissions driving. Once in range extender mode, however, the 1.9-gallon fuel tank (the filler for which is opposite the car’s plug socket) provides enough energy for a further 78 miles of driving, during which time you’ll be emitting 40 grams of carbon dioxide per mile and averaging 39 miles-per-gallon, rather than none at all.

The range extender itself is actually a 650cc two-cylinder unit conveniently borrowed from the German automaker’s two-wheeled division, BMW Motorrad. It develops 34hp and is squeezed directly adjacent the i3’s electric motor on the rear axle.

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A given amount of electricity goes further at lower, urban speeds than it does on the highway, so the BMW i3 Range Extender has a selectable ‘hold mode’. This simply brings the gasoline generator in operation prematurely, maintaing whatever level of charge the battery holds at that point. It means that owners will be able to drive 50 miles, for example, along highways without quickly draining the battery before slipping into electric mode when entering their destination city. As we found out, it’s more pleasant to drive the car at lower speeds in electric mode than range extender mode.

While refueling takes minutes, recharging is the same as the standard i3; around 20 minutes from pDC fast-charging station and three hours from a Level 2 charging station. BMW will provide and install the latter at your home for $1,999.

What’s it like to drive?

A lot of fun. The extra hardware adds 150kg to the weight of the i3, marginally blunting performance and augmenting the sprint to 60mph to 7.9 seconds, but everything that makes electric cars great to drive is there, only turned up a notch. The experience will be new for most people, and it’s hard to adequately put into words the sensation of driving an electric car for the first time (let alone such a fast, well-sorted one), so we strongly recommended test driving one.

Until then, we can say that the ‘surfboard’ battery arrangement that the BMW i3 has in common with the Tesla Model S gives it an assured feel through corners and body-roll is kept in check remarkably well for something with the same ride-height as an MPV.

Forward visibility is also superb thanks to the enormous windscreen, glass front vents, and the position of the seats, which have the driver slightly looking down on the dashboard.

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A highlight of both variants of the BMW i3 is the powerful electric motor. Acceleration is strong and instant at most legal speeds. Top speed, however, is limited to 93mph in electric mode although that will fall in range extender mode as the engine struggles to generate enough power to sustain it. There have been reports of the car slowing down to under 50mph in true ‘limp-home-mode’ fashion.

Overall, the BMW i3 Range Extender is far more entertaining to drive than the Chevrolet Volt, but the tiny fuel tank means longer journeys will require frequent visits to the gas station. If you regularly undertake lengthly stints in the car but want a useable electric range we’d recommend the Volt, which can go around 280 miles on a tank.

Is it refined enough?

The BMW i3 is officially the most efficient electric car money can buy, and one of the reasons why the standard model returns a record 124 miles-per-gallon-equivalent is that it’s very light. This is largely due to the carbon fiber reinforced plastic bodywork and aluminum chassis, but there’s also very little of the heavy sound-deadening materials that you’d typically find in a premium-brand car.

At speeds of 30mph or more this matters very little. While hardly intrusive, tyre roar and wind noise are the loudest sounds in an electric car at those speeds and they hide the hum emanating from the range extender almost entirely. We didn’t even notice the compact oil-burner firing up, in fact, and so for most driving situations it might as well not exist. It’s extremely impressive.

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Slowing down is a different matter, however. The range extender takes a second-or-two to shut off once you come to a complete stop. This may sound like a trivial complaint, but momentarily hearing it chugging away while stationary shatters the Zen-like atmosphere of driving an electric car and is a constant reminder that your very dear and sustainability-built ‘electric car’ isn’t really electric at all. This, however, is only a problem if battery charge is extremely low (around five percent capacity). If it isn’t, the drivetrain will default to pure electric driving every time your speed drops below 15mph.

Another situation where the range extender becomes a slight aural nuisance is if you floor the accelerator. Doing so will force the gasoline generator to work harder in an effort to deliver more electricity to the motor, which of course makes it noisier. We can’t imagine there will be too many situations where you need to drop the hammer in range extender mode, though.

Of course, even for i3 Range Extender owners the majority of driving is going to happen in electric mode, where the car is beautifully serene, particularly with it’s high driving position and spacious cabin.

Should I get one?

This will depend on three things: your geographical circumstances, your finances and your driving ethos.

If you want an electric car but have a lengthly commute or undertake several trips each day, then apart from splashing out on a Tesla Model S there’s simply nothing else available – the Chevrolet Volt only manages around 40 miles in electric mode and it lags far behind the German car in terms of build-quality and enjoyment. If you’ve got the funds don’t hesitate.

At $45,200 the i3 Range Extender is noticeably more expensive than the standard car, however, which is yours for $41,350 (although both qualify for a $7,500 federal tax credit). If you’re paying the surplus because you need the added range then without a doubt it’s money well spent, but if you’re thinking about the Range Extender purely because you’re worried about situations where ‘range anxiety’ might rear its ugly head then we’d advise caution. The standard car is faster, after all, and most people don’t need as much autonomy as they anticipate. The i3 Range Extender is an excellent compromise, but a compromise nevertheless.

That leads us to the third criterion: your attitude. The carbon fiber that forms the BMW i3 is formed using hydroelectric power alone. Each car is then assembled solely using wind power at BMW’s plant in Leipzig, and the interior boasts an array of sustainably sourced materials. The battery-electric BMW i3, then, really is a green car in the truest sense. The i3 Range Extender? Not so much.

The ability to drive forever in a car as polished, relaxing, and enjoyable as the BMW i3 Range Extender is, however, tempting to say the least.

Posted by Richard Lane

Richard is a London-based automotive journalist specialising in future mobility and sustainable design. Having fallen for cars because of the virtues of a particular German flat-six, it's what we'll all be driving next that now interests Richard most. Dream garage: Alfa Romeo GT 1300 Junior and a Detroit Electric SP:01.

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