What is it?
Why did BMW wait for so long to launch a roadster version of the i8? A cynic may suggest that anyone who wanted an i8 had bought one already, and with some three-year lease deals of the early cars now coming to an end, now is a good time to tempt them into something else. Why would you want that 911, sir, when you can have an open-top version of one of these?
After all, a production-ready i8 roadster concept was seen in early 2016, when the i8 coupé was only a year or so into its life, and at that point selling on the used market for more than it was new.
In a world where frequent new variants are crucial to keeping up interest in your sports car no matter how radical yours looks – Porsche the master or stirring the mixing bowl another way every few months – BMW waited to launch this latest version of its sports car until demand had tailed off of the coupé.
At the same time as launching the roadster, BMW has taken the opportunity to upgrade the petrol-electric plug-in hybrid drivetrain of the coupé to the more potent offering of the roadster.
That upgraded drivetrain is focused on the electric side. The front wheels are driven through a 141bhp electric motor – an extra 12bhp from the earlier i8 coupé – and a two-speed automatic gearbox. The lithium ion battery is also larger – capacity rising from 7.1kWh to 11.6kWh – which gives the i8 roadster an electric-only range of 33 miles. It can travel up to 75mph on electric power, too, with charging times also cut thanks to an upgrading charging system.
The mid-mounted 1.5-litre three-cylinder turbocharged petrol engine, which drives the rear wheels through a six-speed automatic gearbox, carries over unchanged. The i8 roadster can therefore run on electric power as a front-wheel-drive car, or an all-wheel-drive car as a hybrid.
BMW says only 60kg has been added to the weight at the kerb of the i8 roadster over the coupé, an impressively low figure, and far less structural reinforcement is needed than normal thanks to the i8 roadster using an aluminium chassis with a high-strength, carbonfibre-reinforced polymer passenger cell.
What’s it like?
Time has been kind to the i8. Just look at it. It still looks like nothing else on the road, and you have to drive around in a hypercar to turn more heads. You get a child-like joy each time you see it and go to drive it. Behind the wheel, you notice passers-by and other road users feeling the same, even if your view out is nowhere as exciting as their view in, roof up or down.
What’s different from the coupé? Not much, in truth. For however radical it is, the i8 is actually quite a typical conversion from coupé to roadster, a beautifully engineered folding soft-top roof mechanism bringing theatre to proceedings as well as dynamic compromises.
Roadsters lose chassis stiffness in their transformation to coupé, and the biggest visual telltale sign is a wobbly interior mirror on the windscreen. The i8 roadster’s doesn’t wobble, though, but try to adjust it and you’ll know why: you need to give it a real forceful tug to adjust it. BMW has made it extra secure. Wonder why?
The i8’s brief has always been open to fairly wide interpretation. Looking at it without any prior knowledge, you’d think it was a hypercar. On price and positioning, it’s a sports car. Spend any length of time in an i8 coupé, and it feels more like a GT.
The i8 roadster feels even more like a GT than the coupé. It’s at its best enjoyed making brisk point-to-point progress on fast, smooth, flowing roads rather than as a memorable companion on your favourite British B-road. It’s properly quick in a straight line, with traction excellent, and in-gear acceleration that’s at times more supercar than sports car thanks to the support of the electric motor.
The sensation of creeping around town in a car as dramatic-looking as the i8 in near total silence on electric power is one of the more unusual in motoring. Yet that sensation now also now comes with some added discomfort, as while the drivetrain might be silent, the chassis isn’t, thumping over bumps and with a low-speed ride that’s choppy at best.
On anything but faster, smoother A-roads and motorways in and around the national speed limit, the i8 is just too darn firm. Not ‘sporty’ firmness, either, more the sort tuned into the suspension to try to mask the lack of body control.
It’s far more fun accelerating out of a corner than slowing down and turning in for one, thanks to a combination of a weird numb and unresponsive feeling in the first half of the brake pedal travel, and a tendency to understeer when pushed. Still, it corners flat and it corners fast, without ever really involving you in anything other than when you floor the pedal on the way out of a corner to enjoy that point-to-point pace once more.
It won’t surprise you to learn the official fuel economy of 141mpg is not an accurate figure – when the battery runs out, you’ll get a fairly steady 35mpg no matter what the road conditions, so divide that by the length of your journey and what you’ll manage to get from the 30 miles or so of electric power to know how efficient it’s going to be for you. But whatever the combined petrol-electric economy is, even at its worst, 35mpg is mightily impressive for a car with such sporting pretensions.
Should I buy one?
Calling things ahead of their time is quite a lazy thing to do, for we should instead adjust our thinking to try to see a creation as its maker.
That’s relevant to the i8 – you know the future won’t look like this, and this car is instead 2014’s vision of the future rather than the present day’s, with everything that’s happened around electric cars and legislation in the intervening period. To that end, I doubt BMW would replace the i8, when electric cars of all types become the norm rather than a special preview of things to come.
In this era, price and layout wise, the i8 is a sports car alternative to a Porsche 911. As a sports car, it just isn’t as good, as either a coupé or now a roadster. As a technological achievement and statement of intent for the way the industry is heading, the i8 is a modern great, and the roadster version that formula made more desirable with nothing more than the usual compromises such a conversion from a fixed roof brings.
Is it particularly engaging? Not really. But then neither is the coupé. Yet the i8 is still beguiling enough to have our blessing, and in its niche class of one, the roadster is the variant to go for. Time and history will be very kind to a car as innovative as this.
BMW i8 Roadster specification
Where Warwickshire, UK Price £124,735 On sale Now Engine 3 cyls, 1499cc, turbocharged, petrol, plus electric motor Power 369bhp (combined) Torque 236lb ft at 3700rpm (petrol engine) and 184lb ft (electric motor) Gearbox 6-spd automatic for petrol engine, 2-spd automatic for electric motor Kerb weight 1595kg Top speed 155mph 0-62mph 4.6sec Fuel economy 141mpg CO2 46g/km Rivals Porsche 911, Jaguar F-Type