The radical BMW i8 has been revealed in its final production form at the Frankfurt motor show.

The plug-in, mid-engined hybrid sports car is the sister car to the new BMW i3. The 4.7-metre-long i8 features the same unusual construction methods, using a carbonfibre-reinforced plastic (CFRP) bodyshell sitting on a welded aluminium chassis. 

BMW claims the i8 can hit 62mph from rest in just 4.4sec with both the engine and electric motor engaged. Top speed — achieved by the petrol engine alone — is 155mph. BMW says this performance is partly thanks to the i8’s relatively low weight of 1490kg and an aerodynamic bodyshell, which has a drag coefficient of 0.26. 

According to the EU fuel economy test, the i8 returns 113mpg on the combined cycle and emits 25g/km of CO2. BMW says the i8 can reach 75mph in its pure electric mode. Weight distribution is “almost exactly” 50 per cent front, 50 per cent rear. The car has three driving modes: Comfort, Sport and EcoPro. BMW claims a range of 310 miles in hybrid mode, or up to 22 miles on lithium ion battery power alone.

The i8 has a 2+2 layout with the three-cylinder engine and generator mounted behind the rear seats, driving the rear wheels. The front wheels are driven by an electric motor and a two-speed automatic transmission, while the battery pack is stored in the centre tunnel, with a petrol tank under the rear jump seats.

The i8’s complex, part-time all-wheel-drive transmission is also of interest because it uses BMW’s new turbocharged 1.5-litre, three-cylinder engine, which will feature in the Mk3 Mini and BMW 1-series

The version of this engine in the i8 develops a remarkable 228bhp, and its specific output of 151bhp per litre is said to be the highest of any production BMW engine to date. The petrol engine — which drives through a six-speed automatic gearbox — and electric motor combined produce peak outputs of 356bhp and 420lb ft. 

In keeping with the i8’s green remit, BMW’s carbonfibre manufacturing plant in the US is powered by zero-CO2 hydroelectricity, while the power at BMW’s i manufacturing plant in Leipzig, Germany, comes from local wind farms.

The i8’s dramatic styling hasn’t moved too far away from that of the original concept. It retains the distinctive ‘overlapping’ panels at the front, around the sills and over the rear wheels, while the C-pillar covers are extended rearwards to form aerofoils. 

LED lights are used front and rear, although buyers will also have the option of unique ‘laser’ headlights, which BMW says are 70 per cent more powerful than LED lights and produce a “pure white, extremely bright light that is pleasing to the eye”.

The i8’s doors are hinged off the A-pillars and open upwards and forwards. BMW says the doors are built around a CFRP and aluminium structure and that all the glass in the car is made from the same chemically hardened mineral glass as that used for smartphone screens. The rear screen lifts up for access to the luggage compartment.

The i8’s interior isn’t quite as radical as the exterior, with a relatively conventional layout, but it gives a good indication of how the cabins of other production BMWs will look in the future.

Click here for more Frankfurt motor show news.