BMW has revamped its i3 with the introduction of a more powerful, 94Ah battery for both the i3 BEV and the i3 Range Extender (REX – petrol powered generator) versions.

The 94Ah versions replace the current 60Ah models and have capacity of 33kWh thanks to the higher storage density of the lithium ion-cells. Battery dimensions are the same but with more than a 50% range increase (tested on the standard NEDC cycle), equivalent to a range of 195 miles (about 300km). The motor accelerates the i3 from zero to 62mph (100km/h) in just 7.3 seconds making, BMW claims, the BEV version "both the sportiest and most efficient electric vehicle in its segment".

Innovative battery

The high-voltage battery in the latest i3s consists of eight modules (each with 12 individual cells) and its capacity has been increased significantly without any changes in structure or exterior dimensions. By optimising the cell-internal packages with more electrolyte and adapting the active material, the automaker has succeeded in increasing cell capacity to 94Ah and overall battery energy to 33kWh.

Lithium-ion cells used in the battery are particularly notable for their high energy density and impressive cycle life: they are designed to perform their energy storage function over the vehicle's entire life span.

The coolant of the air conditioning system is responsible for cooling the high-voltage battery very effectively. An optional heating system can also be used to heat the battery to ensure the optimum operating temperature of 20°C before starting off. The battery has been designed to last for the car's entire service life. Buyers receive an eight-year/100,000 mile (160,000km) warranty on the battery.

Optimised drivetrain

The hybrid synchronous electric motor, developed and produced specially for the i3, generates 170hp and provides maximum torque of 250Nm from rest.

Average power consumption of 12.6kWh/100m on the New European Driving Cycle (NEDC) for the BEV and 11.3kWh/100km for the REX, the efficiency of the motor plays a key role in optimising the car's range newly extended to 195 miles.

BMW therefore claims: "the i3 is the most economical electrically powered car of its size and output class. With significant benefits available from low charging tariffs, the low cost per mile would equate to running a diesel engine and achieving 470.8mpg".

CO2 emissions of the i3 94Ah REX are 12g/km, a 1g/km reduction versus the previous model, while the i3 BEV produces zero emissions "locally".

The power density of the electric motor, weighing around 50kg, sets a new benchmark for electric vehicles, BMW claims.

DC Rapid-charge, previously an option, is now standard. AC charging is now multi-phase, allowing charging of 3.7, 7.4 or 11 kW, a claimed 50% increase versus the previous 60Ah models. Charging time for the 94Ah is now less than three hours, despite the significantly larger battery capacity. As with the outgoing 60Ah, the 94Ah cars can also be charged at home using a standard three-pin plug plug or by installing a [government subsidised in the UK] BMW i Wallbox.

Range Extender

The REX two-cylinder petrol engine (a very compact, Chinese-made unit shared with BMW motorcycle division products) delivers maximum output of 38hp and powers an electricity generator. It operates on "a needs-based and highly efficient principle". As soon as the charging level of the lithium ion batteries drops to a certain level, the generator fires up to keep the charging level constant, extending range by 81 miles (about 120km). Fitting the car with the REX pack (it slots in otherwise unused sub-floor space alongside the electric drive motor) does not impact available luggage volume: its nine-litre fuel tank is installed in the front section with refuelling nozzle under a flap on the right front fender (about the only way to pick a REX in traffic). Luggage compartment volume remains unchanged at 260 litres and can be extended to 1,100 litres with the rear seats folded.

New options, more personalisation

The i3 94Ah is available in the Protonic Blue colour with Frozen Grey metallic highlight. Previously, this paint combo was reserved for the i8 sports car.

Allowing for greater personalisation, interior trims are now available as separate options and are available across all four interior 'worlds', this includes Loft, Lodge, Suite and new Atelier which comes as standard on the i3 94Ah. The Atelier cabin has Neutronic cloth in Aragats Grey with BMW i Blue highlights on the front seats and black leather steering wheel.

New dark oak trim is standard in the Suite interior design. In all other interior designs Dark Oak and eucalyptus wood trim are available as options. The materials used are a mix of naturally treated leather, wood and wool as well as other renewable raw materials.

"These make the sustainable premium character of the i3 both visible and tangible," BMW said.