Open gallery Close by Greg Kable 29 April 2018 Follow @@autocar Share
How we test cars
We’ve waited a long time for the BMW i8 Roadster.
First previewed at the Beijing motor show as the i8 Concept Spyder in 2012, it’s taken a full six years for the plug-in hybrid open-top to be offered in the UK. In that time, the car has undergone a significant amount of development. But, despite the long gestation, it hasn’t lost any of its original impact.
The combination of electric and petrol power provides both brutish four-wheel drive accelerative qualities off the line, and great long-distance touring traits on the open roadGreg KableEuropean editor
Its contemporary exterior design and advanced powertrain specification might be familiar, coming some three years after the launch of the i8 Coupé, but there are few cars at any price that can claim to make such a powerful visual and technical statement as this roadster.
If anything, the i8’s futuristic lines are further enhanced by the loss of its roof, most notably around the rear, which has gained added prominence on the roadster due to the appearance of two large buttresses in the place taken up by the liftback-style tailgate on the coupé.
What else has changed beyond the removable roof?
The roof, which consists of a large fabric panel and integrated header rails, opens automatically in 15 seconds at speeds up to 31mph. It boats near-silent full electric operation and stows vertically behind the two-seat cabin at the press of a button, nestling in a space-saving position between the rear bulkhead and mid-rear mounted combustion engine.
Advertisement Back to top
To accommodate the new soft top, BMW has modified the windscreen of the i8, providing it with a strengthened carbonfibre frame. The rear window, which doubles as a wind deflector, is also altered and can be closed or opened independently of the roof.
Related BMW i8 Roadster 2018-2020 reviews
BMW i8 Roadster 2018 UK first driveBMW i8 Roadster 2018 first drive
Further stylistic changes over the facelifted i8 Coupé that’s set for UK delivery at the same time in June include the deletion of the rear side windows. They are replaced by new panels overlaid with aluminium-look trims with the word ‘Roadster’ on the side of the new buttresses.
In combination with further strengthening measures within the carbonfibre-reinforced plastic and aluminium structure and new frameless scissor-action doors, weight has increased by 60kg over the facelifted coupé at 1595kg.
Inside, the two-plus-two configuration of the fixed-roof i8 has given way to a two-seat layout, with the rear of the cabin altered to provide 92 litres of oddment space within three separate cubby holes in the rear bulkhead. It combines with the 88 litres of the rear-mounted luggage area to provide an overall 160 litres of stowage space.
The earlier dashboard design has also been lightly updated for the i8 Roadster and facelifted i8 Coupé. Among other subtle changes, the latest version of BMW’s iDrive system now offers either touch control on a free-standing 8.8in monitor or via a rotary dial on the middle console.
There are also new seats, an optional head-up display unit as well a range of new trim options, including carbonfibre trim elements for the dashboard and ceramic controls within the centre console.
What mechanical changes has BMW made for the i8 Roadster?
One key change in the powertrain is an increase in output from the front-mounted electric motor. The unit, which was produced in-house, now delivers 12bhp more than it did in the earlier i8 Coupé at 141bhp. This is delivered along with the same 184lb ft as before, through a two-speed gearbox to the front wheels.
Combined with the unchanged 228bhp delivered by the turbocharged 1.5-litre three-cylinder petrol engine mounted transversely up back in a mid-rear position, this provides the roadster with an overall 374bhp and a theoretical maximum torque loading of 420lb ft, although the latter is continually regulated depending on grip and traction levels, with drive delivered to the rear wheels via a six-speed torque converter-equipped automatic gearbox.