BMW i8 Roadster
FIRST DRIVE Hybrid sports car mixes eco tech and open-air fun
IN the four years since BMW launched its i8 Coupé, the company has sold 13,000 of the carbon-tub, petrolelectric hybrid sports cars. Customers have bought into BMW’S i-vision, to the point where they are demanding more from the Bavarian brand, including new models such as the i8 Roadster.
The i8 was never designed to have an open-top version, so BMW’S engineers literally chopped the Coupé’s roof off to see what happened. And when the carbon tub proved rigid enough not to collapse, the firm pressed on with developing the convertible version.
The i8 Roadster’s roof is fully electric, and the switch to operate it is tucked away under the lid for the centre storage compartment. It takes 15 seconds to open or close and there’s a rear window that can be lowered with the roof shut to allow more noise into the cabin.
While the folding roof robs the i8 of its Porsche 911-esque rear seats, BMW does compensate you with an additional 100 litres of storage behind the front seats. The rear boot remains the same as in the coupé, and is big enough for a decent-sized overnight bag.
While the roof may be fabric, the front half has a carbon-fibre panel inserted into it to help maintain its sleek appearance and aid aerodynamics. The only additional strengthening is in the hollow A-pillars and header rail, and is required for the relevant crash tests. The Roadster weighs 60kg more than the Coupé.
Removing the roof also required a few other tweaks to the Roadster’s body, including the fitment of a small splitter behind the front bumper to balance the airflow and prevent the need for a rear spoiler. The vent on the bonnet had to be closed as well – with the hot air from the radiators now redirected under the car, as opposed to over the windscreen and into the now open cockpit. Those trademark butterfly doors are new, too.
Accompanying the external changes, BMW has also fitted the i8 Roadster with its latest edrive technology, which means the capacity of the lithium-ion battery has increased. This provides the electric motor with an additional 12bhp (now 141bhp) and boosts the car’s EV range to 33 miles. This increase in cell density does mean a longer charge time.
That improved battery range is instantly noticeable. Whereas in the original Coupé the electric motor could easily be sidelined by the turbocharged petrol engine, now the electrified elements of the powertrain are far more willing and able to take on longer and quicker driving duties. And when you’ve depleted the batteries, the brake regeneration and the threecylinder petrol motor recharges them much more quickly than before as well.
New spring and damper settings have given the i8 Roadster a more direct front end, although the electric power steering still has little feel,
“The i8 is now far more resolved and inspires more confidence than the earlier Coupé”
requiring a small leap of faith that the nose will go where you need it to. But there’s more grip, less understeer and the tyres work far harder than before.
Through quicker corners and on cresting roads, the i8 is now far more resolved and inspires more confidence than the earlier Coupé. Combine a fully-charged battery with the threecylinder engine – whose turbo you can now hear chuffing away – and the i8 is far more of a sports car than before.
So despite not being built as a Roadster from the outset, the i8 works remarkably well as a piece of design. In fact, with the roof open it’s more striking than the Coupé from every angle. But it still requires an element of physical dexterity to get in or out.