Independent, Expert EV Reviews & Advice Since 2006

The BMW i3 – the world’s most sustainable car?

BMW-i3-Concept-Coupe.jpg BMW is launching a new ‘mid-engined’, rear-wheel drive, lightweight car, with zero g/km CO2 tailpipe emissions, and the company claims that it will be the most sustainable car on sale .

The car that sounds too good to be true is the BMW i3, the first model of the company’s new ‘i’ electric sub-brand, and it’s due to be launched this year. Green-Car-Guide has had an exclusive behind-the-scenes briefing about the i3’s innovations, and we can confirm that electric vehicles have just become much more exciting.

Pure EV and range-extender

BMW i3 structure 001.JPG The i3 is a pure electric car, however it will also be offered with the option of a range-extender. BMW seems to be planning on the majority of people buying the pure electric version. The company expects that the perception of range anxiety will drive some people to order the range-extender version at first, but after a time people won’t see range anxiety as a real issue, and this version may no longer be required.

So BMW expects that the i3 will sell mostly as a pure EV, with a range of 130-160 km, or 80-100 miles. The company’s extensive trials of the MINI E and the Active E (1 Series) show that most people on average only drive around 40 km or 25 miles daily, with the cars being parked for around 22 hours each day.

However there will be the option of specifying a range-extender – although probably not at launch. It won’t be a range-extender like that in the Chevrolet Volt or Vauxhall Ampera , which is a standard GM 1.4-litre petrol engine, but it will have more in common with the system that appears in the Lotus Evora 414E hybrid – in other words the range-extender will be just that – a very lightweight ‘range-extender’ rather than a conventional ‘engine’. It will extend the range of the car to around double that of the EV, but its purpose will be to ‘get you home’ if you run out of electricity – so the car’s performance is expected to be limited in this mode. The range-extender is said to be a small two-cylinder unit from BMW’s motorbike division, but with improved emissions.

Carbon fibre-reinforced plastic structure

BMW i3 structure 003.JPG The i3 has many innovative features, but the big news is the fact that it’s not made out of steel, like most cars, but instead its passenger cell structure is made out of carbon fibre-reinforced plastic (CFRP), with a (painted) plastic outer skin. The benefit of this is that CFRP is light, resulting in the i3, even with a 230 Kg lithium ion battery, weighing just 1250 Kg. This is just slightly heavier than the 1180 Kg of a Toyota GT86 / Subaru BRZ , which is one of the best drivers’ cars that you can buy, and its lightness is a key factor in its excellent dynamics.

CFRP has a number of benefits associated with its light weight. Carbon fibre is a textile, like clothing. It can be moulded to different shapes, and it ends up with a high level of strength. Because traditional cars are made out of steel it means that they’re heavy, but it also means that the production process for the cars involves lots of large, heavy and noisy machinery. Using CFRP means no press or paint shop, no conveyers, and no welding or rivetting. The factory for the i3 is substantially smaller than the size of a conventional car factory, less machinery is required, it’s quieter, and it requires 50% less energy, and 70% less water primarily due to the lack of a paint shop. However it has been a significant challenge to set up large-scale car production using CFRP – involving a new plant (at Leipzig in Germany, where the 1 Series and X1 are made), a new material, and two new products. However it should be remembered that BMW has experience of using carbon fibre, such as in the roof of the M3. The roof of the i3 will feature clear paint, so the carbon fibre structure can be seen.

Sustainability beyond the car itself

BMW i3 structure 005.JPG BMW has also installed four wind turbines to provide electricity for the Leipzig plant – the company claims that these generate more energy per year than the factory requires.

The production of CFRP is energy-intensive, however BMW has established a joint venture with a supplier in America that produces carbon fibre using energy that is 100% generated from renewable hydro-power.

Along with the wind turbines, such initiatives are a key factor in how BMW can claim that the i3 is not only a car with zero tailpipe emissions, but that it has one of the lowest ‘ whole life carbon footprints ‘ of any car on sale. Compared to the manufacture of a BMW 118d, the BMW i3 has just 66% of its lifetime carbon emissions (based on recharging with an average European electricity mix). If the i3 is recharged with electricity generated from renewables, then it has just 50% of the embodied carbon of a 118d.

The i3’s powertrain

BMW i3 structure 002.JPG The largest and most expensive item on board the i3 is its battery – or more accurately, a lithium ion battery with eight modules and 96 cells – and this sits under the floor, and right in the centre of the car. This gives the i3 a very low centre of gravity, and excellent weight distribution – it’s essentially a mid-engined car. It’s also rear-wheel drive. BMW cited the example of the electric MINI E as the reason for this – with its electric powertrain the MINI E had lots of torque immediately available at any speed, which led to torque steer. With the traditional BMW layout of rear-wheel drive, the i3 leaves the front wheels to do the steering, unhindered by any need to transmit power.

BMW has developed the car’s battery and the electronic controller itself, but it purchases the battery cells from Samsung. BMW felt that it was important to source the battery technology from a stable and established supplier; the wisdom of this decision has been proven by the problems that Fisker has had due to its battery supplier going out of business. BMW believes that the batteries will be reliable because of the cooling system that it has developed. After ten years the batteries are still expected to have at least 80% of their performance, and there are plans to re-use any batteries that can no longer be used in cars as energy storage devices, possibly in homes or on a larger scale.


BMW i3 structure 004.JPG BMW has carried out 100 crash tests of the i3; the carbon fibre passenger cell has proven to be extremely safe, and the battery has never experienced any impact. In the event of a crash the high voltage system is separated from the car. The structure can also be repaired by authorised BMW dealers.

BMW says it has proven that a lightweight design can assist, rather than hinder, safety.


Like any electric car, the i3 is most likely to be charged at home. BMW has developed its own wallbox, which can be installed inside a garage, or on an outside house wall. This wallbox enables the i3 to be fully charged in just three hours. It is possible to recharge the car directly from a domestic plug socket, but this is not recommended, and doing so will mean eight hours to fully charge. The i3 can also be recharged from a fast charger, which enables the car to be fully charged in around 30 minutes. BMW has also looked at induction charging and is planning to offer this ‘wireless’ charging option at some stage, but not at launch.

If you buy an i3, BMW says it will offer you the opportunity to change your electricity supply to one that is generated from 100% renewable energy. BMW is also offering a range of ‘mobility services’, such as the ability to use a conventionally-engined BMW for longer journeys. If you do run out of electricity, BMW will send out a vehicle with a ‘charging trailer’, which will provide enough charge in 15-20 minutes at the side of the road to get you to a static charge point.

i3 launch

The i3 is being launched this year. Prices have not yet been confirmed, but estimates are between £35,000-£40,000. BMW has made a significant investment into the development of the i3, and i8, and not surprisingly it needs to make a return on its investment. And remember that carbon fibre is expensive.

Unlike Renault’s strategy of selling their EVs and leasing the battery separately, the i3 will always be sold as a complete car with the battery, making residual values easier to forecast.

The i3 will be followed by the launch of the i8 in 2014. The i8 will share much of its technology with the i3, but it’s a supercar, and so the powertrain is more powerful – it will be a 3-cylinder, 1.5-litre petrol engine mated to a battery and electric motor.


BMW says that the development of the i3 and i8 is ‘uncharted territory’. The company wants to position itself as a leader and pioneer, however in practical terms, the i brand is required in order to help BMW meet future European vehicle CO2 targets.

Our favourite quote from the i3 event was that the ‘future belongs to those who dare’. Based on what we’ve seen so far, BMW has certainly been daring and deserves to win.

Paul Clarke


Related articles:

BMW i Mobility

BMW i: “The future is green”

Electric Car Guide Video

Electric vehicles eligible for the UK government’s Plug-in Car Grant

Report on vehicle whole life carbon emissions