In our First Drive and Quick Spin of the 2014 BMW i3 electric car and our follow-up Comparison Test of the BMW i3 and Chevrolet Volt, we noted how the i3’s lightweight carbon-fibre construction and aluminum platform contributed to its class-leading acceleration and surprisingly nimble driving manners – but we were less impressed with the i3’s unusual exterior and interior styling, its impractical rear-hinged rear doors, and the aggressive braking effect of its regenerative charging system once the right foot is released from the gas pedal.

And while we noted that the i3 has a longer electric driving range than many electric cars, it is still only a quarter of a conventional car’s range. BMW quotes an ‘everyday’ electric range of between 130 and 160 km in standard Comfort mode while the EPA quotes a more realistic average range of 130 km. The i3’s electric range can be extended slightly by using the driver-selectable Eco Pro and Eco Pro+ modes which restrict top speed and air conditioning use.

For those worried about being left stranded with a dead battery, BMW makes available an optional ($4,000) range-extender 647 cc two-cylinder gas engine with 38 horsepower that can extend the i3’s total driving range up to a claimed 300 kilometres. The EPA says the i3’s total range is closer to 240 km.

Unlike the range extender engine in the Chevrolet Volt, the i3’s small 647-cc engine is not intended to be an alternative power source for the battery; rather, it is designed as a backup should the i3 driver not be able to charge the battery before the charge runs out. The i3’s gas engine doesn’t drive the wheels or power the electric motor or completely recharge the battery: it merely creates a minimum charge in the lithium-ion battery to keep the I3 going for up to 100 kilometres or so. However, a BMW rep told me that if you were to drive uphill for an extended period using the range extender, it would not be able to maintain enough charge to keep going.

Given the amount of money (reportedly $2.9 billion) and new technology that went into the development BMW’s electric car program, I suspect the BMW intended the i3 to be a pure electric vehicle, but included the range extender option to satisfy consumers unfamiliar with electric car operation who may have range anxiety. This was a good decision because currently about 50 percent of i3 buyers choose the range extender option.

I decided to see for myself how far the i3 would go on electric power alone before the range extender kicked in. My test was conducted in mostly sunny, dry weather between 20 and 25 degrees – probably the ideal conditions for an electric car. I didn’t need to turn on the air conditioner or the heater that week, saving valuable electrical energy as we drove. But if this test was conducted in the middle of a very cold Canadian winter, you could probably knock 25 perent off the range distance.

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