BMW confirms i8 will drop its top

BMW has confirmed that its electrified i range will be expanded to three models with the addition of a plug-in hybrid i8 Roadster that is expected to be formally unveiled at September’s Frankfurt motor show ahead of its showroom rollout next year.

The company made the confirmation of the second i8 body style – complementing the existing two-door Coupe launched in Australia in 2014 – via a teaser video of a camouflaged pre-production mule in wind tunnel testing.

The Roadster is expected to join an updated i8 Coupe and its smaller sibling, the i3, in Australia, although timing remains under wraps.

Although details are scant, the Roadster appears to have a targa-style fabric folding roof that European reports suggest folds away behind the seats.

The side-rear windows have been deleted and the glass rear hatch replaced with a flat vertical glass pane behind the cockpit.

The i8's floating aerodynamic curves towards the roofline remain, but now terminate as twin buttresses. Thankfully, the scissor-style dihedral doors will not be lost in translation.

Updated LED headlights – including the Bavarian company's new hexagonal design – are expected to be shared with the Coupe when it gets a mid-life update – or Life Cycle Impulse (LCI) in BMW language – in 2018.

Likewise, the Coupe is also expected to share fuel efficiency improvements with the Roadster, which BMW says consumes 2.0 litres of fuel per 100 kilometres on the combined cycle test, while emitting 45 grams of carbon dioxide per kilometre. This compares with the current Coupe’s 2.1L/100km and 49g/km.

The rumour mill is going into overdrive with suggestions the i8 Roadster will employ a more powerful version of the Coupe's prevailing petrol/electric powertrain combination, as well as a larger battery pack for increased electric driving range.

As it stands, a 170kW/320Nm 1.5-litre turbocharged three-cylinder engine is paired with a 96kW/250Nm electric motor for a total system output of 266kW/570Nm, helping to knock down the sprint to 100km/h in 4.5 seconds.

The internal combustion unit sends drive to the rear wheels via a six-speed automatic transmission, while the electric motor powers the front axle, creating on-demand all-wheel drive.

The current i8 Coupe is priced from $303,300 before on-road costs in Australia. No doubt the Roadster will command a premium over Coupe pricing, but we do not expect that to be confirmed until closer to launch next year.

Sales for the sportscar have slowed this year, with only 10 examples finding homes in Australia to the end of May, down from 17 last year.

Without a direct rival, i8 finds itself pitched against the Mercedes-AMG GT and Audi R8, which have mustered 56 and 19 units respectively in 2017.

When i8 Roadster arrives, it will be a long time coming considering i8 Concept Spyder broke cover at the Beijing motor show in April 2012, providing a glimpse of the still-in-gestation production car.