نویسنده : مهدی محمدی تاریخ : جمعه بیست و نهم مهر 1390
BMW i8 Concept
The BMW i8 Concept and the fascinating approach that underpins it embody the vision of a sustainable contemporary sports car brought to life. Its innovative plug-in hybrid concept combines the modified electric drive system from the BMW i3 Concept - fitted over its front axle - with a high-performance three-cylinder combustion engine producing 164 kW (220 hp)/300 Nm (221 lb-ft) at the rear. The electric motor in the BMW i8 Concept is a full-capability unit which can also power the car on its own, if required. However, working in tandem allows the two drive systems to display their respective talents to the full, delivering the performance of a sports car but the fuel consumption of a small car.
Acceleration of 0 to 100 km/h (62 mph) in under five seconds combined with fuel consumption in the European cycle of under three litres per 100 kilometres (approx. 94 mpg imp) and average customer fuel consumption of between five and seven litres per 100 kilometres (40.4 - 56.5 mpg imp) - even when driven hard - are figures currently beyond the capability of any vehicle powered by a combustion engine of comparable performance. Thanks to its large lithium-ion battery, which can be charged from a domestic power supply, the BMW i8 Concept can travel up to 35 kilometres (approx. 20 miles) on electric power alone. A large proportion of short everyday journeys can therefore be completed with zero emissions. The car's electric-only mode allows it to enter emissions-capped central areas of cities with access restrictions in place for petrol or diesel-powered vehicles. The i8 Concept's efficiency rating is further enhanced by its ability to generate energy at both axles. The electric motor at the front axle recoups maximum energy every time the driver brakes, while a high-voltage alternator hooked up to the combustion engine charges the battery, if required. Added to which, the 2+2-seater offers enough space for four people, giving it a high level of everyday practicality.
The emotional design of the BMW i8 Concept ensures its qualities are clear for all to see. Its dynamic proportions give the BMW i8 Concept the appearance of surging forward before it even turns a wheel and lend visual form to its extraordinary performance. The sophisticated concept behind the upward-swivelling doors fixed to the A-pillars underlines the car's sporting capability and opens up access to the front and rear seats at the same time.
A series of air inlets allow the air to flow through and around the vehicle to optimum effect, ensuring extremely low drag. They also add visual emphasis to these advanced aerodynamics. Airflow plays an extremely important role at the rear of the vehicle as well. Intakes behind the passenger cell and at the rear provide a cooling flow of air through the engine compartment, while outlets in the rear diffuser and the flow of air around the rear wheels ensure the car is extremely efficient in terms of lift and downforce at both axles.
The LifeDrive architecture of the BMW i8 Concept has been carefully adapted to enhance the vehicle's sports car character, and therefore to deliver unbeatable performance and excellent driving dynamics. The motor in the front axle module and combustion engine at the rear are connected by an "energy tunnel", which houses the high-voltage battery. This gives the car a low centre of gravity - and the dynamic benefits that come with it. The positioning of the electric motor and engine over their respective axles and the space-saving and well-balanced packaging of all components result in an optimum 50/50 weight distribution.
The weight of every component inside the BMW i8 Concept has been minimised down to the very last detail, allowing the extra weight of the electric drive system and battery to be cancelled out. The BMW i8 Concept therefore presents the ideal environment in which to sample this very special drive concept on the road. The passengers sit - in typical sports car style - in an extremely low and enclosed position inside the CFRP-constructed Life module (mounted above the Drive module).
The sporting character of the BMW i8 Concept continues into the interior. Boasting a driver-focused environment unmatched by any BMW Group vehicle before it, the BMW i8 Concept immerses the driver fully in the unique driving experience. The purpose-built driver's position is geared squarely towards the person at the wheel and gives optimum access to all information and controls. The three-dimensional displays are crystal clear and flash up the relevant information for the driving situation at hand. The interior as a whole is defined by the functionality of a classical BMW sports car and majors on lightness and ease of use. The BMW i8 Concept is the sports car for a new generation - pure, emotional and sustainable.
The LifeDrive architecture
The BMW i8 Concept sees the LifeDrive architecture concept adapted to suit the vehicle's sports car character - i.e. primed to deliver leading performance and sharp dynamics. This interpretation of the LifeDrive concept takes its cues from the innovative hybrid concept of the BMW i8 Concept, which links up an electric drive system at the front axle with a combustion engine over the rear wheels to lay on an unparalleled driving experience.
In a departure from the purely horizontal configuration favoured for the BMW i3 Concept, the LifeDrive architecture of its BMW i8 Concept sibling also features vertical layering in the front axle module, passenger cell and rear axle module. The drive systems powering the BMW i8 Concept are integrated into the front and rear axle modules, with the CFRP Life module providing the bridge between the two. As a plug-in hybrid, the BMW i8 Concept is not designed purely for all-electric propulsion, and therefore carries fewer battery cells than the BMW i3 Concept. These are stored in the Life module inside an energy tunnel, a structure similar to a central transmission tunnel. The front and rear axle modules therefore combine with the passenger cell and battery to form a functional unit, which adopts not only load-bearing responsibilities but also extensive crash functions. The location of the high-voltage battery in the energy tunnel gives the vehicle a low centre of gravity, and this enhances its dynamics. Together with the positioning of the motor and engine over the axles, the result is optimum 50/50 weight distribution. Intelligent lightweight design and the innovative use of materials produce extremely low unsprung and rotating masses, which is good news for the car's driving dynamics, acceleration, range and fuel economy. All in all, the BMW i8 Concept offers the ideal environment in which to experience the special drive concept and distinctive sports car character of the BMW i8 Concept on the road.
The BMW i8 Concept's axles are designed to deliver optimum handling properties, in keeping with the car's sporting profile. The multi-link front axle provides the ideal geometric platform for an extremely flat and aerodynamically efficient silhouette. The front axle construction is also designed explicitly to handle the twin demands of the steering and drive system. It eliminates any drive forces which may otherwise affect the steering, ensuring optimum handling in every situation.
In the CFRP Life module passengers sit low down and enclosed - in classical sports car style - between the motor and engine. Between them runs the energy tunnel that intersects the interior. Swivelling doors fixed to the A-pillars provide large openings that allow access to both front and rear seats. Four seats make the BMW i8 Concept a practical everyday vehicle that brings together the full array of positive BMW attributes.
Innovative laser lighting
The BMW i8 Concept is already showcasing the next logical step in the evolution of passenger car lighting technology: laser lighting. BMW engineers hope to have this latest cutting-edge technology in production in just a few years' time. As well as providing a basis for completely new lighting functions for further enhanced safety and comfort, this new light source is also more efficient, which could have a significant effect in terms of energy and fuel consumption.
By definition, laser lighting is radically different from sunlight, and also from the various types of artificial lighting in common use today. For a start, laser lighting is monochromatic, which means that the light waves all have the same length. And it is also what is known as a "coherent" light source, which means that its waves have a constant phase difference. As a result, laser lighting can produce a near-parallel beam with an intensity a thousand times greater than that of conventional LEDs. In vehicle headlights, these characteristics can be used to implement entirely new functions. Also, the high inherent efficiency of laser lighting means that laser headlights have less than half the energy consumption of LED headlights. Simply put, laser headlights save fuel.
The intensity of laser light poses no possible risks to humans, animals or wildlife when used in car lighting. Amongst other things, this is because the light is not emitted directly, but is first converted into a form that is suitable for use in road traffic. The resulting light is very bright and white. It is also very pleasant to the eye and has a very low energy consumption.
Completely safe laser lighting technology is already in use in a variety of consumer products, though in many cases this is a product feature that goes unnoticed by the customer. That won't be the case when this technology is used in cars, however, as planned by BMW. Here the whole point is that the advantages should be noticeable and visible. A further feature of laser technology, which has important implications, is the size of the individual diodes. With a length of just ten microns (μm), laser diodes are one hundred times smaller even than the small, square-shaped cells used in conventional LED lighting, which have a side length of one millimetre. This opens up all sorts of new possibilities when integrating the light source into the vehicle. The BMW engineers have no plans to radically reduce the size of the headlights however, although that would be theoretically possible. Instead, the thinking is that the headlights would retain their conventional surface area dimensions and so continue to play an important role in the styling of a BMW, while the size advantages could be used to reduce the depth of the headlight unit, and so open up new possibilities for headlight positioning and body styling.
A further advantage of laser lighting technology, and one which the BMW engineers intend to use to full effect, is its high inherent efficiency. A single statistic will make this clear: whereas LED lighting generates only around 100 lumens (a photometric unit of light output) per watt, laser lighting generates approximately 170 lumens. With statistics like this, it is not surprising that BMW is also planning to take advantage of laser lighting technology to increase the efficiency of the overall vehicle. And appropriately enough it is in a concept vehicle from the new BMW i sub-brand, the BMW i8 Concept, that laser lighting will get its first airing. After all, BMW i stands for a new premium concept that is strongly oriented towards sustainability.
Best of both worlds
Whereas the BMW i3 Concept always drives on electric power, the i8 Concept combines the advantages of two different drive systems - an electric motor and an internal combustion engine. As a plug-in hybrid it offers the best of both worlds, combining maximum efficiency with maximum performance. A 0-100 km/h (62 mph) acceleration time of under five seconds, combined with fuel consumption in the European test cycle of less than 3 litres/100 km (approx. 94 mpg imp) and average real fuel consumption of between five and seven litres (40 - 56 mpg imp) even with a fast driving style are figures unrivalled by any conventional internal combustion-engined vehicle in this power class. Depending on charging habits and the nature of the route, it is even possible to improve on these figures. The secret is the intelligent configuration of the two drive units. In the BMW i8 Concept, the electric motor is not a secondary power source but an equal partner of the internal combustion engine. In this way the BMW i8 Concept achieves a new, ideal balance between the two drive units which results in an optimal combination of efficiency and dynamism.
The electric motor has been adopted from the BMW i3 Concept and modified for use in the BMW i8 Concept's hybrid power train. It drives the front axle, while a 164 kW/220 hp turbocharged three-cylinder petrol engine developing up to 300 Nm (221 lb-ft) of torque drives the rear axle. Together, the two drive units take the vehicle to a governed top speed of 250 km/h (155 mph). Like the electric motor, the 1.5-litre three-cylinder petrol engine was developed entirely in-house by the BMW Group and represents the latest state of the art in conventional engine design. The pairing of these two drive units in the BMW i8 Concept reflects the outstanding expertise of the BMW Group in the development of both engines and electric motors.
The energy supplied by the application-designed battery system installed between the front and rear axle modules to the electric motor at the front axle gives the BMW i8 Concept an all-electric driving range of approximately 35 kilometres (20 miles). The battery can be fully recharged in two hours at a standard power socket. The electric motor of the BMW i3 Concept has been specially modified for use in the plug-in hybrid power train of the BMW i8 Concept, i.e. for operation with a smaller battery pack and in conjunction with an internal combustion engine.
A highlight of the BMW i8 Concept is the high-voltage generator attached to the internal combustion engine, via which the internal combustion engine can generate power for recharging the batteries. This option is only used to increase the range of the vehicle while out on the road, and is not intended as a substitute for stationary recharging at an electric power socket.
Maximum performance in all driving situations
Although the BMW i8 Concept has all-electric capability, the big attraction of this vehicle lies in the combination of the two different propulsion systems. The BMW i8 Concept combines the high-torque responsiveness of an electric motor with the power of an internal combustion engine, a field in which BMW has specialised for many decades. The BMW i8 Concept makes the most of the specific advantages of the two propulsion systems, which complement and support each other perfectly. The two power sources dovetail smoothly to compensate for any loss of power during gear changes. The combined result is that the BMW i8 Concept provides very dynamic acceleration performance across the entire road speed range.
All four wheels of the BMW i8 Concept can be driven at the same time, similarly to an all-wheel-drive vehicle. This solution combines the driving dynamics advantages of front-wheel drive, rear-wheel drive and all-wheel drive. An optimal drive configuration can therefore be provided to suit all driving situations.
When accelerating on dry roads, for example, maximum traction is available at all four wheels, resulting in better driving dynamics and driving enjoyment even when pushing the vehicle hard. In winter, too, the two separately driven axles provide benefits, the four intelligently driven wheels making for enhanced safety on slippery roads and keeping the vehicle moving under almost all winter conditions.
The fact that the electric motor is located at the front axle of the BMW i8 Concept optimises braking energy recuperation, since the front axle is where greater braking forces are developed due to the dynamic wheel load shift when decelerating. Whenever there is a chance to recuperate braking energy, intelligent driving dynamics systems make the most of it, taking into account traction conditions and driving situation, without compromising stability and dynamics. This allows very high levels of braking energy recuperation even in the wet or in snow. Depending on requirements, braking is initially provided by the recuperation function and only when more powerful braking is required is the conventional brake system engaged.
Efficient and dynamic
The design of the BMW i8 Concept is as special as the car's overall concept, embodying the perfect synthesis of technology and aesthetic allure. Its sweeping lines and flat silhouette lend the vehicle a strikingly dynamic appearance even when standing still. Taut surfaces and precise edges combine to form an extremely sculptural and organic surface structure. The BMW i8 Concept appears to have been cut from a single mould, with the front end, flanks, rear end and roof flowing smoothly into one another. Dynamic surfaces and forms generate attractive light and shadow effects, which add emotional emphasis to the car's light and sporty character. A large, transparent greenhouse lends the exterior an extraordinary feeling of lightness and highlights the exceptional efficiency of this vehicle concept. Short front and rear overhangs round off the sporting overall impression. Despite its dynamic appearance, the 2+2-seater can accommodate four people, giving it a high degree of everyday practicality.
As with the BMW i3 Concept, layering again serves as the central design element of the interior and exterior. The individual vehicle components are also clearly visible from the outside, the black and transparent Life module clearly setting itself apart from the silver-coloured body components around it. The overlapping surfaces and carefully positioned joints enable a reduction in the number of parts required and therefore also a drop in the car's weight. Indeed, the airflow-optimising surface structure can meet aerodynamic requirements without the addition of extra body elements. This layering approach lends the BMW i8 Concept an extremely technical and cutting-edge appeal.
Dynamic side view
The precise lines along its flanks and hallmark BMW i "stream flow" give the BMW i8 Concept a strong sense of powering forward even when it is standing still. Plus, the compact packaging of the electric motor over the front axle has allowed the designers to give the car an extremely low and aerodynamically efficient front end. The BMW i8 Concept's doors swing upwards like wings to provide an undeniably emotional and sporting allure. The high-strength carbon passenger cell allows large door openings which give access to the front and rear seats at the same time. Like the rest of the exterior, the construction of the doors is shaped by the overlapping of several layers of material. Below the doors, the silver-coloured layer moulds the car's flanks into a powerful wedge shape, opening out from the door sills towards the rear. A blue flourish accentuates the dynamic presence of the sills. Together, the bonnet and door sill sculpting emphasise the BMW i8 Concept's forward-surging stance, and their smooth lines imbue the car with an extra lightness.
Striking front end
The BMW i8 Concept also displays its dynamic sports car persona when viewed from the front. A number of different levels interact with one another in the design of the front end, while sculptural air intakes and channelling ducts evoke a feeling of depth. The expressive surface treatment exudes dynamic verve and advertises the car's sporting potential. The broad kidney grille and flat headlights emphasise the car's low-slung and dynamically wide-set stance. The full-LED headlights of the BMW i8 Concept also adopt the signature BMW i U-shape with two adjacent arches. Set back slightly into the body and framed by a U-shaped surround, the headlights give the car a sporty and urbane appeal.
A black, semi-transparent "V" rises out of the bonnet just behind the kidney grille, opening out towards the windscreen and guiding the eye to the electric motor below. The "V" also offers the first glimpse of the CFRP module and extends back towards the rear like a black band to provide a visual connection between the different sections of the car.
Sporty rear end
Similarly to the front end, the rear of the car is also very low, horizontal and sculptural in design. The silver-coloured side sections form a striking vertical frame around the rear of the car, with a precise line extending out to the sides enjoying particular prominence. This line also serves as a spoiler lip and emphasises the aerodynamic efficacy of the rear end. In its centre the silver-coloured and blue-framed rear diffuser is a wider and lower interpretation of the version on the BMW i3 Concept, adding a distinct sporting flavour to its relationship with its stablemate.
In this area of the car the exceptional sporting credentials of the BMW i8 Concept are expressed in width-accentuating lines, three-dimensional air outlets and "floating" tail lights with air through-flow. The tail lights, which also have a distinct horizontal design, are integrated into the upper layer of the rear and share the signature U-shape of the BMW i light concept.
BMW i8 Concept: putting the dynamic into aerodynamics
The efficient aerodynamics of the BMW i8 Concept can be seen in a host of different details. Numerous parts of the car's body serve as air guidance elements. Narrow openings around the front apron guide the inflowing air into two AirCurtains. These enclosed ducts channel the air along the inside of the front apron to the wheel arches, where it is expelled at high speed through an extremely narrow outlet, brushing past the tyre sidewalls as it goes. The out-rushing jet of air hangs like a curtain over the sides of the front wheels and minimises turbulence in this area. Added to which, the car's underbody is totally enclosed and has a smooth surface to counteract the under-car turbulence that would otherwise push up fuel consumption. Meanwhile, the hallmark "stream flow" on the sides of the car highlights its optimised air flow and air channelling capability. Moving further back, the structures above the tail lights and the large air outlets underline the reduction in drag achieved over the vehicle as a whole
The transparent surfaces in the doors and roof give the exterior and interior design of the BMW i8 Concept the appearance of merging into one another. The clear forms of the interior provide an attractive contrast to the dynamically flowing exterior and lend the cabin a special lightness and dynamic flair. The colour concept and underlying structure of the BMW i8 Concept interior closely mimic those of the BMW i3 Concept. Here again, the Porcelain White support structure, black technical level and comfort section with Mocha Brown leather are split into three different layers. Stream Blue touches on the centre console, instrument panel and seats lend stylistic expression to the efficiency and sustainable character of BMW i in the interior. Naturally tanned leather and warm colours underline the light, high-quality and sustainability-focused ambience inside the BMW i8 Concept. A light felt with three-dimensional meshing provides the floor covering and emphasises the dynamic flavour of the interior as a whole.
The arrangement of the air vents, control panels and displays also betrays the car's family ties to its BMW i3 Concept sibling. Overall, however, these features have a more sporting character and are geared much more clearly towards the driver. Indeed, a level of driver focus beyond that of any BMW Group vehicle before it allows the BMW i8 Concept to immerse the driver fully in the unique experience behind the wheel. The purpose-built driver's position puts the driver squarely at the centre of the action and gives him easy access to all information and controls. The three-dimensional displays are extremely clear and flash up the relevant information for the driving situation at hand. At the same time, occupants in the BMW i8 Concept sit in a highly integrated position low down in the car and are separated by the battery running lengthways through the interior. This longitudinal bisection of the cabin underlines the sporting and forward-looking character of the BMW i8 Concept interior. Like a road map above the passengers' heads, the organic, longitudinal structure of the transparent roof reflects the inspiration for the car and its key focus on delivering a dynamic driving experience.
Layering in the interior
The driver-focused design can also be seen prominently in the distinctive layering of the interior. Surfaces, levels and joins form functional areas and mark them out from one another. For example, the interplay of various levels gives the driver's area a very three-dimensional design and clearly sets it apart from the front passenger area. In a clear gesture towards the person behind the wheel, the lines around the driver all converge into the binnacle to form an extremely focused driver's position. Driving functions such as the gearshift lever, start/stop button and parking brake are arranged around the driver on the centre console and are also extremely driver-oriented graphically.
The driver's position also dominates a second level within easy reach of both driver and front passenger. This is where they will find the iDrive Controller with touch-control surface and the climate control unit. The central information display, meanwhile, is positioned above the instrument panel. The freestanding design of the unit gives it a particularly intricate and high-quality feel. The instrument panel integrates the controls for the audio and climate control system almost seamlessly into the surrounding surface. They are illuminated with LEDs, giving them a very pure touch-control look. However, their button-based design allows them to provide feedback through the fingertips, accentuating the sporting character of the BMW i8 Concept.
Here again, the layering concept fuses functionality and stylishly minimalist design to innovative effect. Elements such as the central air vents not only have the task of enhancing comfort, they also form part of the cockpit architecture. At the same time, the use of layering also gives visual form to the principle of lightweight design in the interior and, together with the generous amount of exposed carbon in the Life module, emphasises the car's low weight. The rear seats are fixed solidly to the floor, but at first glance they appear to be floating, giving this area of the car a light and contemporary feel.
Two large displays give the driver access to the relevant information for the driving situation at hand and help him to operate connectivity-related applications. The 8.8-inch (22.4 cm) central information display is joined by an equally large display taking the role of the instrument cluster. Indeed, its high-quality presentation in the binnacle makes it look far larger. In normal driving mode the two drive systems are depicted by a pair of ellipses, which supply information on their operation at any given time. Other information - such as the available range and fuel level - can be found here, too, and the driver can also call up three-dimensional navigation instructions in addition to the other readouts. The displays in this area share the high-quality, modern and pure design which has been established as a hallmark of BMW i. In ECO PRO mode the displays turn blue in colour, confirming the change in functional emphasis, while an efficiency display tells the driver how much further the car can travel before recharging or refuelling, and shows the optimum accelerator position to maximise efficiency. If the driver switches to Sport mode, the colour of the display information changes to orange and the ellipses rotate and point in the direction of travel. A large readout of the car's speed is displayed digitally between the ellipses. This extremely dynamic display concept brings the emotional driving experience to the screens and, with its uncomplicated approach to showing information, helps sharpen the driver's focus on the primary task at hand. In every driving mode, this display concept ensures the driver is shown the information he requires at that moment in time to do the best possible job of piloting the car.
- Length: 4632 mm
- Height: 1280 mm
- Width: 1955 mm
- Wheelbase: 2800 mm
- No. of seats: 2 + (2)
- Kerb weight: 1480 kg
- Combined: 260 kW (550 Nm)
- Petrol engine: 164 kW (300 Nm)
- Electric motor: 96 kW (250 Nm)
- Top speed: 250 km/h (155 mph) [limited]
- 0-100 km/h (0-62 mph): 4.6 s
- 80-120 km/h (50-75 mph): 4.0 s
- Fuel consumption (EU cycle): 2.7 l/100 km (104 mpg imp)
- CO2: 66 g
- Electric range: approx. 35 km (20 miles)
- Battery charge time
- Standard: 1:45 h for 100% charge
- Luggage compartment: approx. 150 litres
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