share on BufferFollowing the recent unveiling of the i3, BMW has now presented the production-ready version of the i8, the advanced 2+2 sportscar featuring a plug-in hybrid drive system, a passenger cell made from carbon-fibre- reinforced plastic (CFRP) and an aluminum frame.
The aerodynamic exterior design (Cd: 0.26) is strongly based on the i8 Concept revealed in 2011, in turn derived from the 2007 Vision EfficientDynamics, with its distinctive surface treatment made of overlapping and interlocking forms and characterized by the layering principle.
Above: comparison between the 2011 i8 Concept (top) and the new production version (bottom)
The main differences are concentrated in the side view, where the original dark-tinted transparent panels have been replaced by conventional painted body surfaces and the slightly tilted waist line has been left out in favor of a more horizontal border.
BMW designers have maintained the “black belt” which emerges in a “V” shape from the hood and extends back over the roof into the rear section of the car, where it frames the centre section of the rear apron.
Other design elements derived from the concept include the “floating” rear pillars that flow into the rear end and the butterfly door opening system.
For the interior, the design team has managed to adopt almost all the main elements of the original, high-tech cockpit – quite unusual for a volume-produced car, even if it’s such a peculiar model.
Above: the interior of the i8 Concept (left) and the one of the new i8 production version
As a result, apart from the more concept-esque parts – the cabin maintains a unique personality and an extremely futuristic look.
From a technical perspective, the plug-in hybrid system features a three-cylinder, twin-turbo 1.5-liter gasoline engine delivering an output of 170 kW/231 hp,coupled with a six-speed automatic gearbox and with a synchronous electric motor with an output of 96 kW/131 hp driving the front wheels via a two-stage automatic transmission; the lithium-ion high-voltage battery has liquid cooling and a usable capacity of 5 kWh.
The extensive use of advanced materials allowed to maintain the total weight below 1,500 kg. The announced prices will start at $135,700. The market launch is expected for spring 2014.
Below we report the official details form BMW’s press release.
From the official Press Release:
Exterior design
The design of the BMW i8 body is as groundbreaking as the plug-in hybrid sports car’s concept as a whole. Hallmark BMW dynamics, lightweight design and efficiency are all expressed in the car’s proportions, lines and surface design.
The 2+2-seater is immediately recognizable as a BMW i model and a new-generation sports car.
The structure of overlapping and interlocking surfaces – lent additional emphasis by the car’s color concept – also contributes to the unmistakable appearance of the BMW i8.
This layering principle allows aerodynamic forms to be wrapped up in a progressively styled package, while powerfully formed wheel arches draw attention to the wide track of the BMW i8.
The compact construction distinguishing both the electric motor and combustion engine allows the front and rear sections of the car to be particularly low-slung and thus accentuate the car’s dynamically stretched flanks. The doors, which open forwards and upwards like wings, add extra intrigue to the sports car design of the BMW i8.
A signature feature of BMW i cars is the “black belt”. On the BMW i8, it emerges in a “V” shape from the bonnet and extends back over the roof into the rear section of the car, where it frames the centre section of the rear apron. At the front end, the black belt is framed by the body-coloured apron and side panels, while at the rear it is overlapped by the “floating” roof pillars, which extend over the rear lights. Another element of the standalone BMW i design language is the “stream flow” contour of the side window graphic.
On the BMW i8 the stream flow also determines the path travelled by the air between the falling roofline and the character line rising through the rear section of the car’s flanks towards the rear spoiler lip.
The front view of the BMW i8 exudes sporting ability in its purest form. Large front apron air intakes arranged over several levels generate a powerful feeling of depth.
The extremely broad BMW kidney grille stretches over to the slim headlights, accentuating the width of the BMW i8 and its road-focused stance. The car’s full-LED headlights adopt the hallmark U-shape of BMW i models. The dipped and high-beam light is emitted by a lens positioned on the far outer edge of the light units. Next to it is the Motorway Light, an auxiliary headlight which enables a significantly improved light range when driving on motorways and cross-country routes at 120 km/h (75 mph) and above. The three-dimensional design of the light sources lend their appearance a sporty character.
The low-slung stance of the rear end and its horizontal, width-emphasising lines also provide a clear showcase for the dynamic potential of the BMW i8. The rear is bordered by the sculpted rear wheel arches. The sloping rear window opens high, allowing easy access to the storage compartment located underneath. The rear lights, reflectors and rear diffuser form a single visual unit that strengthens the car’s already powerful appearance. Like the headlights, the intricately designed rear light clusters also feature the characteristic BMW i U-shaped design. The direction indicators are integrated above the rear lights into the downsweep of the roofline. All of the lights on the BMW i8 are LEDs as standard.
Visible efficiency: aerodynamic optimisation on a detailed level.
The BMW i8 boasts a drag coefficient (Cd) of 0.26 and a fine aerodynamic balance. The low-slung bonnet, almost totally blanked off kidney grille, Air Curtains in the front apron, sealed underbody, contoured side skirts, “stream flow” lines of the car’s flanks, and the air ducts between the rear lights and roof frame allow the air to be channelled extremely effectively as it hits the car.
The large, comparatively slim wheels with their bespoke, aerodynamically optimised design also help to quell efficiency-reducing turbulence – and their effect is reinforced by aeroflaps positioned behind the front wheels and ahead of the rear wheels. Precisely defined air flow across all areas of the body provides a balance between air resistance and lift designed to maximise driving dynamics and directional stability.
The paintwork adorning the side body panels and front and rear ends of the BMW i8 can be specified in a choice of four colours, three of which have been created exclusively for BMW i. All the paint finishes provide a striking contrast to the black belt. And, depending on the colour chosen, the accent surfaces on the side skirts, at the rear and on the BMW kidney grille surround come in BMW i Blue or Frozen Grey.
Interior Design
Future-focused design also dominates the interior of the BMW i8. The driver orientation typical of BMW cockpit design is complemented by progressive elements which highlight the sports car’s dynamic flair and light weight. The driver, front passenger and rear passengers sit low down – in traditional sports car style – in lightweight seats.
The standard leather trim extends beyond the seat surfaces to parts of the centre console, instrument panel and interior door panels. The use of leather treated with natural substances, including olive leaf extract as a tanning agent, underlines the sustainable character of the BMW i8 alongside its exclusivity and sporting allure. Exposed CFRP sections of the passenger cell visible around the entry apertures when the doors are opened provide a reminder of the low weight of the BMW i8.
The instrument panel of the BMW i8, with its horizontal lines emphasising the width of the interior and a structure determined by the “layering” principle, creates a light yet powerful impression. The arrangement of the overlapping, three-dimensional segments is complemented by a contrast-rich colour scheme.
The layering approach also finds its way, through dynamically curving lines, into the design of the centre console, which is home to the gearshift lever, the Controller for the iDrive operating system, the start/stop button, the eDrive button and the Driving Experience Control switch. The iDrive system’s Control Display comes in a freestanding 8.8-inch format. A bespoke sports steering wheel with multifunction buttons and the Navigation system Professional are included as standard in the BMW i8. Also standard is the multifunction instrument display, whose content and presentation formats take their cue from the driving mode selected.
Available as alternatives to the standard Neso trim for the BMW i8 interior are the Carpo and Halo equipment lines. In standard specification, the contrast between black surfaces in the cockpit and light Carum Grey leather surfaces emphasises the lightness and sustainability of this vehicle concept. The leather surfaces of the door and side trim are complemented by functional textile highlights made from recycled material. The optional Carpo equipment line is available in light or dark versions. The naturally treated leather surfaces feature perforated elements and subtle contrast stitching which underline the superior character of the material and workmanship involved. Painted surface elements on the instrument panel, door trim and centre console add the finishing touches to the cutting-edge ambience.
The likewise optional Halo equipment line brings a pervasive aura of luxury and sustainability to the interior of the BMW i8. Top-quality leather surfaces combine with textile accents and contrast stitching in BMW i Blue. And when it comes to the colour scheme, dark Dalbergia Brown and light Carum Grey provide attractive contrasts. The Halo line also brings high-class paintwork to selected instrument panel and door trim surfaces. The accent ring for the leather steering wheel comes in BMW i Blue in the Halo equipment line and in Satin Silver in the other variants.
(Source: BMW)
Although I have forgotten most of my aerodynamic knowledge since I left the Uni, I am a bit concerned with the “stream side contour” stated.
Since this sports car is supposed to carry people safely at high speed, I hope BMW has taken into account that such described features, with aerodynamic prominence, could not only increase the noise in the cab, but lead to some unpredictable behavior in certain (but possible) occasions which are not easy to recreate in a wind tunnel test or using fluid dynamic software.
For example, in the aeronautic field we study how an unpredictable wind stream flowing with certain angle against the plane´s moving direction, must make a commercial aircraft react in such way that it recovers its normal dynamic movement. If this occurs, the plane is dynamically “stable” and requires no help from the pilots to return it back to the previous dynamic status. Otherwise, the plane could start an unstable behavior with fatal consequences or needing software help to return to a “stable mode” of flight (just as modern fighters and drones which are, paradoxically, extremely agile due to this fact. On the other side, that’s why commercial planes have such conservative design and all of them look almost like 60 years ago).
Hence, a 250km/h – lightweight car speeding on a german autobahn in such case, should have efficient aerodynamic devises to provide such stability in case of unpredictable wind stream or e.g, when it is overtaking a huge lorry/truck on the other lane, whose messy whirlwind could activate an erratic car behavior. Let’s take in mind that wind effect is proportional to square velocity which obliges not to underestimate certain sceneries.
In conclusion, I hope the BMW engineers must have thoroughly motorized the design process.
RAL, very interesting insight, thanks for sharing.
BMW ignores to mention that the designer Richard Kim has left the company and is now working for VW…