The much-discussed Roadster features an electric folding soft-top, stored in a space-saving vertical position. It can be raised or lowered in 15 seconds, and is operable at speeds up to 50km/h. There's also a rear windscreen that can be raised and lowered independently.
The addition of a roof mechanism and structural reinforcements has made the i8 a bit heavier, but the Roadster still weighs just 1595 kilograms, or around 60kg more than its coupe sibling.
While the coupe can seat four in a pinch, the roadster is a pure two-seater. With passengers to worry about, there's around 100 litres of storage space behind the front pews.
Both coupe and Roadster variants use a new 11.6kWh battery pack, up from the outgoing model's 7.1kWh unit. Top speed is 120km/h in pure-electric mode, while driving range is up to 53km in the soft-top, and now 55km in the coupe.
There's also an upgraded electric motor, which has gained 9kW. Now rated at 105kW of power and 250Nm of torque, the electric motor drives the front wheels.
The unchanged 170kW/320Nm 1.5-litre turbocharged three-cylinder petrol engine drives the rear wheels. Working in concert, the combined powertrain has a claimed output of 275kW.
Top speed in both the coupe and roadster is 250km/h. Flat out, the Roadster requires 4.6 seconds to complete the 100km/h dash, while the coupe can complete the same run in 4.4s.
Other changes include new front seats, revised interior trim options, and 'Coupe' or 'Roadster' badging around the C-pillar.
Standard features on both the coupe and roadster include a fast charging cable, the Professional satellite navigation system, the company's latest iDrive system, a freestanding 8.8-inch screen, dynamic damper control, automated emergency braking, cruise control, and a 2.2-inch touchscreen display built into the key fob.
The roadster also features standard 20-inch wheels, and a unique suspension and stability control setup.
Options on both models include head-up display, laser high beam system, and an acoustic pedestrian warning system, which operates at speeds up to 30km/h when the car is operating in electric-only mode.
The new BMW i8 Roadster and the updated i8 Coupe go on sale globally from May 2018. We're waiting to hear back about local timing.