SPY PICS: BMW i8 Spyder looms

It is some time ago – late 2015 in fact – that BMW confirmed it was intending to introduce a folding-roof Spyder version of its i8 supercar. Now, it appears to be on track for an expected launch some time in 2018.

These spy photos shot recently in northern Sweden show the open-air i8 will be more Targa than convertible, with a canvas aperture sited between the top of the windscreen and the "roll-bar" section extending between the B-pillars.

Two flying-buttress-style pods, more or less replicating the coupe roofline, extend from behind each seat to the tail lights, presenting an open rear deck that is overseen by a near-vertical, flat-paned rear window at the B pillar.

Otherwise, the rear end, including the tail lights and general architecture, is pretty close to that of the coupe's. Presumably the doors hinge from the same points as the coupe to give a gullwing-style effect.

As for the powertrain, word is the i8 will benefit from a general upgrade that involves a new 10kWh battery pack to increase the EV driving range by as much as 50 per cent, as well as a tweaked version of the three-cylinder 1.5-litre petrol engine producing more punch than the current car's 170kW/320Nm. It's also being reported that there will be a rework of the 96kW/250Nm electric motor that drives the i8's front wheels.

It's likely the Spyder's weight will creep up over the coupe's 1485kg but, given the minimalist nature of the soft roof and the presumption that little structural change was required, hopefully not by too much.

One would have to reckon that, with the power tweaks, the Spyder's performance will be similar to, or better than, the current i8 coupe, which is credited with a zero to 100km/h acceleration capability of 4.4sec.