The BMW i8 is the second model from BMW’s new i brand. Driven here for the first time in prototype form, the low slung coupé is planned to go on sale in the UK next April at a price that will, BMW officials hint, pitch it into direct competition with the conspicuously more conventional Porsche 911 Carrera 4S, which retails here for £87,959.

A more extrovertly styled roadster version of the advanced hybrid, which boasts an official fuel consumption figure of over 113mpg and average CO2 emissions in hybrid mode of under 59g/km, is also under development at BMW’s Munich-based R&D centre, although it isn’t likely to see local showrooms until 2015.

Billed as a progressive sportscar, the i8 was first shown in concept car guise at the 2009 Frankfurt motor show. At the time, it ran a diesel-electric hybrid system. However, it has since made way for a petrol-electric set-up that shares various components, including its main electric motor, with the BMW i3’s exclusively electric driveline.

Like its smaller sibling, it can run in pure electric mode, but only for distances of up to 22 miles and a top speed of 75mph owing to its relatively small battery. Overall range promises to be quite spectacular thanks to a 42-litre fuel tank that is mounted underneath the rear seats. BMW is not prepared to make a figure official but it is already quite clear that the i8 will be among the most fuel efficient sportscars ever placed into production.

The i8’s styling has evolved during the four-year development phase, although the basic silhouette and flamboyant layered body design has been retained, giving the i8 a strikingly futuristic external appearance which is carried through to the snug two-plus-two interior. Length, width and height are put at 4689mm, 1942mm and 1293mm respectively, making it 449mm longer, 152mm wider and a scant 3mm taller than the second-generation BMW Z4 – a car against which the new BMW has been extensively benchmarked.

As with the i3, the i8 makes extensive use of carbonfibre and aluminium in a bid to offset the inherent weight of its advanced driveline. A so-called Life Module fashioned from carbonfibre forms the main structure, to which BMW has attached carbonfibre-framed doors and aluminum sub-frames both front and rear.