2018 BMW i8 Roadster review

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Despite looking a lot like an i8 Coupe with a missing roof, the extensive reworking involved to create the i8 Roadster ensures this new variant upholds BMW’s technical edge while still turning heads like nothing else on the road.

Sports cars tend to have something of a short span when it comes to sales success. Once the newness wears off, sales start to taper.

In order to prevent such a thing from happening to the BMW i8, the German company did what many manufacturers have done before it, rolling out the usual incremental specification changes in concert with a much more substantial change: the addition of a new Roadster variant.

Of course, the idea of a drop-top i8 is nothing new. Even before the i8 Coupe went into production in 2014, BMW had already shown an i8 Spyder concept as part of the 2012 Beijing motor show. Although that car and a later 2016 concept differ in their details, both set the tone for what BMW had in mind for its open-air plug-in hybrid sports car.

Perhaps the most significant change between Coupe and Roadster versions is the elimination of the rear seats. In their place, BMW has created the area into which the roof stows, upright, along with a 92-litre storage cavity behind the front seats.

Look a little more closely and you’ll also see the Roadster boasts new doors. Although the A-pillar hinged butterfly opening mechanism remains, the Coupe’s framed glass has been deleted for the Roadster, thanks to new carbon-fibre door assemblies skinned in aluminium.

The drop-top transformation adds an extra 60kg of weight, some of it from the electrically operated roof itself (which takes 15 seconds to deploy and can be operated at speeds of up to 50km/h), and some from additional bracing added to the rear along with higher sides for the carbon-fibre passenger cell to ensure minimal loss of rigidity for the new variant.

Beneath the wild vented skin, the updated i8 range features an extensively reworked powertrain. Although the 170kW and 320Nm 1.5-litre three-cylinder turbo-petrol engine is unchanged, BMW has bumped up outputs from the electric side.

The e-motor driving the front axle now claims a maximum of 105kW and 250Nm (up 9kW) and is paired with a new 34Ah high-voltage lithium-ion battery (previously 20Ah), which extends the i8’s electric-only range to 55km in the Coupe (previously rated at only 37km), while the Roadster can manage 53km.

The electric system operates through a two-speed transmission instead of the usual EV single-speed system, while the petrol engine runs through a six-speed auto. Charging takes two hours to reach 80 per cent or three hours to reach 100 per cent from a 16A outlet, or 4.5 hours to fully charge from a 10A wall socket.

While both power sources are networked together to create an all-wheel-drive system for performance driving, the EV side of things can provide sole power at speeds of up to 105km/h (70km/h previously) in normal driving or up to 120km/h with the dedicated eDrive mode selected.

Of course, if you demand more than the electric system alone can give, the i8’s petrol engine will kick in, bringing an intriguing but addictive engine noise that’s part three-cylinder symphonics and part artificial assistance. The best part about the Roadster is that with the top down you get more of the rather unique-sounding exhaust noise (though it’s still part artificial) and notice less of the sound system’s contribution.

Selecting Sport mode is another way to have both engine and motor on call at all times, and this is the one to pick for slingshot acceleration. BMW claims a 4.6-second 0–100km/h sprint from the Roadster and a 0.2-second reduction for the Coupe, which matches the time for the pre-update Coupe.

Specs are all well and good, though, but it’s not until you’re settled behind the wheel that the i8 really comes into its own.

BMW launched the i8 Roadster in the city of Palma de Mallorca, off the coast of Spain, starting off from the centre of town before winding along the coast and finally veering into the mountains as an ideal showcase of the new roadster’s ability.

With a freshly topped up battery and a city of ambling traffic, a fleet of i8s took to the streets, almost silently gliding though Palma’s avenues propelled by nothing more than their electric motors, with only a sight electric whine signalling that the cars were exerting themselves in any way.

Before long, though, the motorway beckoned, and even though the i8 could potentially hit the 120km/h limit without touching a drop of fuel in eDrive, there’s simply no better feeling than slamming the right foot to the firewall, adding a wail of good old-fashioned internal combustion roar and slingshotting from freeway entry ramp onto the open road ahead.

Although eDrive lets you pick pure EV driving, the i8’s logic will, in most situations, give the zero local emissions side of things a fair go when left in Comfort thanks to changes to the powertrain control to optimise the e-motor’s contribution.

Sport mode – which runs both powertrains simultaneously – is great fun, but simply leaving the i8 in Comfort, where it can make its own choices about which powertrain to use, makes the most sense for less demanding driving.

With the roof down, sunshine streaming in, and stitching together a series of tightening radius bends and picturesque sweepers along Mallorca’s rough-hewn coast, the often silent i8 Roadster evokes the sensation of sailing.

Whereas a traditional sports car might provide a constant soundtrack for the action taking place between the driver and the road, the i8 usually glides along bringing the surrounding ambient noise (and a hint of wind rustle) to the fore, with an occasion burst of fat-sounding three-cylinder bark into the mix as the driver demands.

Suspension work for the Roadster includes retuned springs, dampers and stability control, with the end result being a sports car free from harsh ride or uncomfortable firmness. Although Mallorca’s roads aren’t exactly Australian conditions, there are still plenty of rough sections and poor-quality surfaces that the i8 Roadster was able to absorb surprisingly well.

It’s clear that BMW hasn’t simply made a stiffly sprung car with leaden steering in an attempt to amp up the sportiness of the i8. Instead, there’s a more delicate touch to the suspension and steering (itself lighter than you might expect) to position the Roadster as something of classic grand tourer rather than a bone-jarring monster.

That’s not to say the speed potential isn’t monstrous, though. While the combined total powertrain output is a calmish 275kW (in the context of European sports cars), there’s nothing particularly shy about being able to scramble to 100km/h in 4.6 seconds.

Of course, there are less expensive fully electric sedans from a particular American disruptor that claim times of more than two seconds less, but point one of those at a corner and it simply won’t have the body control, the feedback, or the feeling of the i8 – let alone the ability to refuel within minutes (using petrol) to extend the journey.

Inside, BMW has kept most of the i8 Roadster’s design as before, although there are new seats that help reduce wind buffeting compared to those of the Coupe, and the latest version of BMW’s iDrive infotainment that adds touchscreen functionality and a revised menu layout.

Delve a little deeper and BMW has gone to the lengths of trimming the audio system speakers behind the headrests in fabric, like a home hi-fi system, which is an auto-industry first apparently, to ensure no undue wind noise is created, while the bass drivers in the cabin cargo area are aimed downwards to minimise the impact of luggage riding along in the cabin.

Although the rear ‘+2’ seats are now gone, the cabin is all the better for it in terms of functionality. Not only that, but using a soft top (which includes metallic threads for a premium look) meant the Coupe’s sleek profile could be maintained without the need to add an awkward storage solution for the roof.

The one obvious area where the Roadster misses the mark is cabin access. The new high-sided carbon-fibre passenger cell makes sliding in and out of the cabin just a touch more difficult. Almost the antithesis of the graceful arc of the doors as they open – I’d suggest a few practice runs at home before venturing out in public, perhaps.

After a drive route of 196km, the i8 Roadster reported fuel consumption of 6.4L/100km, above the claimed 2.0L/100km official figure (which it’s worth noting is based on only the first 100km of travel), but still impressive considering the fairly severe whipping the poor thing copped.

Pulling up at the end of the trip even indicated around 3km of electric range left, although the second half of the journey was mostly EV-free with only small gains in range picked up via regeneration from downhill coasting.

It’s worth noting too, the i8 avoids the stepped feel of some regenerative brake systems as it switches from e-braking to friction braking, but even under a hard stop, the brakes don’t quite feel as aggressive as they probably should.

There’s also a slight seat of the pants drop in accelerative urge when the e-motor is less able to contribute to the overall performance package. Despite that, there’s never a sensation that the i8 has reverted to a pedestrian econo-car. It still rewards driver inputs and there’s no sudden change of personality.

Even though BMW has positioned this car as a halo (for the i sub-brand at least), there are a few details that seem to be missing. Only little things, but adaptive cruise control still isn’t available, nor is blind spot monitoring, with BMW taking the high road on aesthetic purity over advanced driver aids that would create unsatisfactory styling protrusions, apparently.

Absent top-end tech seems a little off for such a high-end product, but at least it upholds the theory of a pure driver’s car.

Ultimately, the i8 – either Roadster or Coupe – is always going to be a niche product, something BMW freely admits, with no delusions of hunting down cars like the Porsche 911 in the sales race. That said, with over 10,000 deliveries under its belt since launch, BMW does get to claim the title of the world’s most popular plug-in hybrid sports car.

It’s fairly obvious that this isn’t a car for all tastes, and certainly not for all budgets. Australian pricing will be revealed closer to launch, but with the pre-update Coupe priced from $303,300 plus on-road costs, the Roadster can only head north.

Of course, there are cars that are faster, more practical or more efficient, but there’s really nothing quite so in your face without spending supercar money. Nor is there anything right now with a sports car skew that rolls together the kind of technology automakers will be forced to adopt thanks to the tightening emissions regulations of the future.

Innovation is what BMW i is all about, after all. Whether you choose to do that in a Coupe or a Roadster is irrelevant. What matters is that the i8 represents good, clean fun that you can have right now instead of waiting for the future to arrive.