It has been six years since BMW first teased its open-top plug-in hybrid sports car at the 2012 Beijing motor show as the i8 Concept Spyder, and now we're finally driving it.
The last six years has also seen a significant amount of development and, despite taking over half a decade to arrive, it hasn’t lost any of its original impact.
Its contemporary exterior design and advanced powertrain specification might be familiar some three years after the launch of the original i8 coupe, but there are few cars at any price that can claim to make such a powerful visual and technical statement as the new BMW.
Vehicle Style: Small hatchback
Price: $325,000 (estimated)
Engine/trans: 275kW/570Nm 1.5 litre 3cyl turbo petrol electric | 6sp automatic
Fuel Consumption: 2.0l 100km
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 coupe.
The roof, which consists of a large fabric panel and integrated header rails, opens automatically in 15 seconds at speeds up to 50km/h. It boasts near-to-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.
To accommodate the new soft top, BMW has modified the windscreen of the i8 providing it with a strengthened carbon fibre frame. The rear window, which doubles as a wind deflector, is also altered, and can be closed or opened independently of the roof.
Further stylistic changes over the facelifted i8 Coupe that is set to reach Australian showrooms at the same time as the i8 Roadster later this year include the deletion of the rear side windows. They are replaced by new panels overlaid with aluminium-look trims carrying with the word 'Roadster' with the side of the new buttresses.
In combination with further strengthening measures within the carbon-fibre reinforced plastic and aluminium structure and new frameless scissor-action doors, weight has increased by 60kg over the facelifted Coupe at 1595kg.
Inside, the two-plus-two configuration of the fixed roof i8 has given way to 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 reduced 88-litres of the rear mounted luggage 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, with the latest version of BMW’s iDrive system now offering either touch control on a free-standing 8.8-inch monitor or rotary control via a dial on the middle console featuring among other subtle changes.
There are also new seats, an optional head-up display unit as well a range of new trim options, including carbon fibre elements for the dashboard and ceramic controls within the centre console.
ON THE ROAD
Key among the changes brought to the powertrain of the i8 in the creation of the new Roadster is an increase in output from the front-mounted electric motor. The in-house produced unit now delivers 9kW more than with the earlier i8 Coupe at 105kW, which is delivered along with the same 250Nm as before through a two-speed gearbox to the front wheels.
The increased reserves of the electric motor are combined with the unchanged 170kW and 320Nm delivered by the turbocharged 1.5-litre three-cylinder petrol engine mounted transversely up back in a mid-rear position with drive going to the rear wheels via a six-speed torque converter equipped automatic gearbox.
All up, the electric motor and combustion engine provides the i8 Roadster with 275kW and a theoretical maximum torque loading of 570Nm.
Further modifications have also been made to the lithium-ion battery, which is mounted wholly within the centre tunnel. While similarly dimensioned to the unit used previously, its cell capacity has been raised from 20 to 34Ah. The use of fourth-generation cells have also increased its energy capacity from an earlier 7.1 to 11.6kWh.
As a result, BMW quotes a pure electric range for the i8 Roadster of 53km - some 16km more than it claimed for the earlier i8 coupe. Top speed in electric mode is limted to 120km/h.
As well as recuperating energy under braking, the new BMW uses the an electric motor at the rear as the i8 coupe. It acts as a generator to top up the battery on the overrun.
Around town in eDrive ECO mode, progress is whisper quiet and quite urgent as the upgraded electric motor provides drive exclusively to the front-wheels. But with a turning circle of 12.3 metres overall manoeuvrability in tight urban conditions certainly isn’t one of this car’s biggest strengths.
But don’t let anyone tell you the i8 Roadster is lacking for speed. There are quicker cars at this price point, granted. But the combination of electric and petrol power in Hybrid Drive Sport mode provides the new BMW with both brutish four-wheel drive accelerative qualities off the line together with great long distance touring traits on the open road. There is excellent flexibility across a broad range, and once you’ve wound on sufficient revs there’s also a gruff engine note, too.
BMW quotes an official 0-100km time of 4.6sec, with acceleration from 80 to 120km/h put at a claimed 2.6sec. Top speed in hybrid mode is limited to 250km/h.
Despite changes to the suspension bushings and a new vertical strut for improved wheel control at the rear, there remains some annoying tyre roar on less than smooth surfaces. However, the secondary vibrations through the carbon fibre body structure, both from the road and engine, are now much better damped than with the earlier i8 coupe in a move that helps improve overall refinement.
Further improvements have been focused at the steering. It receives new mapping, which brings greater sensitivity around the straight ahead. It’s still quite light by sportscar standards, but there’s now added weight off centre. Overall, it endows the i8 Roadster with a more responsive feel than the older i8 coupe, allowing you to place it more confidently in corners and indulge in its excellent dynamic capabilities.
There’s a multi-faceted appeal to the i8 Roadster you don’t find in any obvious open top rival. You can cover large distances with effortless progress and great economy, switching in and out of eDrive Eco mode into Hybrid Drive Sport as the conditions allow. The driving position is excellent with fittingly sporting qualities within an interior that is appropriately high on quality.
TMR VERDICT | OVERALL
It may have been a long wait, but the i8 Roadster does not disappoint. The changes BMW has brought to both its powertrain and chassis not only endow it with sharper performance but also more endearing driving qualities than the earlier i8 coupe.
With the adoption of these changes, the fixed roof version of the headlining BMW i model also promises to take a step up the sportscar ladder.
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