BMW i8 2018 revealed in LA

BMW whipped the covers off its facelifted i8 Coupe at the Los Angeles motor show overnight, with the two-door model to also be offered in a Roadster form for the first time when it lobs in Australia during the middle of next year.

Featuring an upgraded powertrain that now produces a total system power output of 275kW, the plug-in hybrid sportscar is 11kW more powerful than the pre-facelift Coupe.

The mid-mounted 1.5-litre turbocharged three-cylinder petrol engine returns, once again producing 170kW and 320Nm, but its front-axle electric motor partner has upped the ante by 9kW, to 105kW, while torque is unchanged at 250Nm.

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The i8 will also be offered in a Roadster form for the first time.

The former picks up a particulate filter and sportier exhaust note, with drive sent to the rear wheels via a six-speed automatic transmission, while the latter employs a two-speed unit.

Significantly, the i8's 355-volt lithium-ion battery has an increased energy capacity of 11.6kWh (up 4.5kWh) and battery cell capacity of 34Ah (up 14Ah).

It takes less than three hours to full recharge the battery when using a fast-charge outlet, or about 4.5 hours if plugging into a domestic power supply.

Weighing in at 1535 kilograms – up 50kg – the four-seat Coupe zips from 0-100km/h in 4.4 seconds while on the way to an electronically limited top speed of 250km/h – or 120km/h in 'EV' mode.

Its pure-electric driving range swells by 18 kilometres to 55km, while claimed fuel consumption has improved by 0.2 litres per km to 1.9L/100km on the combined cycle test. Carbon dioxide (CO2) emissions have dropped by 7 grams per km to 42g/km.

The Roadster can drop its electrically operated fabric roof in 15 seconds at speeds up to 50km/h.

Comparatively, the two-seat Roadster is 60kg heavier, 0.2s slower to triple digits, 0.2L/100km less efficient and 4g/km more pollutant. However, it has the same top speed and is just 2km shy in terms of pure-electric driving range.

First teased as an i8 Spyder concept at the 2012 Beijing motor show, the Roadster can drop its electrically operated fabric roof in 15 seconds at speeds up to 50km/h.

The mechanism fully retracts into the rear-end to stow in a perpendicular position, which adds 100 litres of extra storage space behind the seats, complementing the 80 litres of luggage capacity in the rear boot.

The i8's trademark frameless dihedral doors have been redesigned for the Roadster.

Furthermore, the retractable rear window rises by 30mm when the roof is lowered, acting as a wind deflector.

The i8's trademark frameless dihedral doors have been redesigned for the Roadster and are constructed from carbon-fibre reinforced plastic (CFRP) with an aluminium outer-shell. CFRP is also employed by other body panels, including the entire windscreen frame and side skirts.

Supplementary struts and panels were added to the front and rear axles to improve rigidity, as is required when removing a traditional roof structure.

Inside, changes over the pre-facelift model are miniscule.

While the Roadster is identified by 'Roadster' badges on its C-pillars, the Coupe has traded in its side windows for a similar treatment, with 'Coupe' designations now in their place.

Inside, changes over the pre-facelift model are miniscule, but the latest version of BMW's 'iDrive' multimedia system features, as do redesigned seats, and new upholstery and colour scheme options.

Australian pricing and specification will be confirmed closer to local launch of the i8 Coupe and Roadster. For reference, the current i8 Coupe costs $303,300 before on-road costs.