BMW has developed a new, more capacious battery pack for its i3 electric hatchback to increase the car’s range, and that very power unit has finally found its way into the REX range-extender variant.

For those uninitiated in the complexities of the i3 range, the REX model is essentially an electric car, just like the standard i3, but fitted with a tiny two-cylinder petrol engine to reduce those feelings of range anxiety. Technically speaking it isn’t a hybrid, because the internal combustion engine doesn’t actually power the wheels – it just charges the battery up a bit.

The result is a 276-mile range that comes at a cost of just 12g/km CO2 emissions. And if you use the electric motor solely as a get-out-of-jail-free card, you’ll hardly ever need any fuel.

Driving an i3 has always been something of a bold statement, what with the seemingly floating body panels and recycled cabin materials, and the REX looks more or less identical to the fully electric car. Unless the minute motor is actually running, the chances are that nobody will notice that this i3 has an internal combustion engine.

As with the standard electric i3, then, some will love it and others will hate it.

In the cabin, you get the same premium, space-age feel that’s interspersed with the occasional oddity, such as the plastics made from plant fibres.

Some of the ergonomics take a little getting used to, as well, including the chunky gear selector that protrudes from the steering column. The build quality is excellent, though.

With its tall stance, the i3 provides plenty of headroom for even the tallest passengers, and the electric motor’s compact dimensions mean it doesn’t struggle much with legroom, either.

Despite the i3’s front-wheel-drive layout, it’s quite fast

The boot is more or less comparable with other superminis and city cars, with the 230-litre volume far outstripping the 196 litres offered by a Toyota Aygo but falling short of the 280 litres found in the back of a VW Polo.

Despite the i3’s front-wheel-drive layout, it’s quite fast. The 0-62mph time is up there with warmed-up hatchbacks and the instant torque of the electric motor makes it feel even faster. It steers well, too.

Where the i3 feels best, though, is in town. The nippy 0-30mph time is perfect for the vigour of urban driving, and the high driving position provides decent visibility. The range-extending engine, however, is most noticeable when driving at low speeds, where its incessant thrum can’t be drowned out by the tyre roar.

In all fairness, though, even BMW says the engine is best used on motorways, where vehicle speeds are higher and the electric motor consumes more juice.

So if you leave it in electric mode in town and switch the engine on when you get to the A-roads and motorways, you’ll hardly notice the on-board power station.

The equipment fits with BMW’s premium positioning and includes satellite navigation, climate control and automatic lights and wipers.

At a glance

Engine
Electric motor (168bhp)

Transmission
Single-speed fixed-ratio gearbox
driving the front wheels

Performance
0-62mph in 8.1 seconds

Top speed
93mph

Economy
470.8mpg

Emissions
12g/km

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