First shown as a concept car at the Beijing Motor Show in 2012, the BMW i8 Concept Spyder showed what a roofless version of the i8 Coupé might look like. Featuring ingenious packaging and dihedral doors, despite the design challenges of not having a fixed roof, the latest addition to BMW’s extensive model range is now available at a substantial £124,735, before FCD discounts are applied.
An all-season fabric soft-top, with high-level soundproofing and all-electric operation, ensures the roof opens and closes silently in 15 seconds and while travelling at up to 31mph. The three segments of the roof fold vertically in a Z-shape, thus taking up very little space and leaving an additional 100-litres of storage capacity between the roof box and the seats. This is in addition to the 88-litres of cargo space in the rear compartment.
Lightweight design and innovative technology play a key role in the car’s construction, with aluminium elements connecting the roof to the body of the car being made using 3D printing processes. The rest of the structure comprises an aluminium chassis and a CFRP passenger cell that offers an exceptional degree of design freedom. The car’s C-pillars are adorned with model-specific badges bearing the Roadster inscription, repeated on the tail.
The low bonnet, the BMW kidney grille, air flap control system, air curtains in the front apron, sealed underbody, contoured side skirts, ‘stream flow’ lines, of the car’s flanks, and air ducts between the rear lights and roof frame allow the car to channel airflow more effectively. Equipped with enormous 20-inch light-alloy wheels, each of which weighs one kilogram less than the lightest wheels previously available for the i8, customers can also choose from three light-alloy wheel variants, of similar dimensions. Full-leather upholstery clads the cockpit with a combined cloth/leather trim as an option.
Driven by a hybrid synchronous electric motor and a three-cylinder, 1.5-litre petrol ‘assist’ engine, power is fed to the rear wheels through a six-speed Steptronic transmission, while the electric motor propels the front wheels via a two-speed automatic gearbox. The end-result is a hybrid-specific all-wheel-drive system that provides the i8 with assured stability.
Underpinning its improved emissions-free range is an updated version of the i8’s lithium-ion battery. The high-voltage unit is located centrally under the car, and its cell capacity is increased from 20 to 34Ah, which means that there is more energy at its disposal. The improved technology means the i8 Roadster can cover up to 33 miles with zero emissions, broadening the reach of all-electric mobility well beyond most city limits. The Roadster is capable of pulling away and reaching speeds of up to 65mph purely on the electric motor’s power, making it possible to drive with zero emissions not just in town, but on country roads too. If the eDrive button is depressed, the all-electric threshold is increased to 75mph.
The i8’s petrol engine now develops a maximum output of 231bhp from its displacement of just 1.5-litres, plus a peak torque of 236lbs ft. It is refined and generates a sportier note, when called upon. The system output produced by the electric motor and engine acting in unison has increased to 374bhp, which allows the car to clock 0-60mph in 4.6 seconds before hitting its electronically limited top speed of 155mph. The Official Combined fuel consumption stands at 141.2mpg, allied to emissions of 46g/km. Most owners will range between 40 to 56mpg in regular use.
The i8 Roadster’s high-end chassis technology is based on a double-wishbone front axle and a five-link rear end, featuring aluminium components engineered for optimum weight and rigidity. Dynamic Damper Control, specially configured steering characteristics, a firmer roll stabilisation set-up and precise tweaks of the DSC parameters ensure pristine handling and performance qualities. Its unladen weight is 1,595kg, only 60kg more than the Coupé version.
The BMW i8 was the world’s first production vehicle to be equipped with non-dazzling laser headlights. They have a remarkable high-beam range of up to 600 metres, double that of a full-LED set-up. An acoustic pedestrian warning, which makes it easier for pedestrians to hear the vehicle approaching, makes a sound like a ‘turbine’ to add to the space-age offering. The new Roadster also benefits from the latest digital connectivity services, which include intelligent route planning, complete with refuelling stops at either charging stations, or service stations. The BMW Display Key and BMW Connected, for smartphones and smartwatches, allow the vehicle status to be checked at any time, including fuel level, battery charge, range and service information, all viewable on its 2.2-inch touchscreen display. It can also be used to operate the door locks and power windows.
Under the umbrella of 360° ELECTRIC, mobility in the i8 Roadster becomes a convenient and practical experience. Supplied with a mode 2 charging cable as standard, the high-voltage battery can be recharged from a standard domestic, three-pin socket in under four-and-a-half hours. The new mode 3 cable can also be used to hook up the car to a public charging point for high-power charging. The BMW i Wallbox makes home charging particularly easy and convenient.
