Only a concept so far
Wayne Gerdes - CleanMPG
- Aug. 29, 2009
BMW Vision PHEV-31 -The latest BMW Concept Car following the EfficientDynamics philosophy to its natural conclusion.
Having followed BMW closely since pre-launch of the 335d and F 800 GS bike here in the US and the EfficientDynamics 1 and 3-series vehicles overseas, the more I learn, the more excited I become.
Just as enhancements to the dynamic ability of each BMW creates a lasting and sustainable brand value, BMW’s EfficientDynamics engineering philosophy resulted in the most dramatic drop in fleet consumption of any automaker from 1990 through 2005.
Today, the BMW Vision concept car demonstrates that the EfficientDynamics objectives are fully compatible when applied to a sports car. Conceived as a 2+2-seater with plug-in full-hybrid technology, this unique car combines the performance of a BMW M vehicle with a standard of fuel efficiency and emission management that exceeds the most fuel efficiency achieved by the latest diesel sub-compacts and mid-sized HSD equipped hybrids. This outstanding result is made possible by the combination of BMW ActiveHybrid components, an economical diesel combustion engine and outstanding aerodynamics.
BMW Vision EfficientDynamics is the result of a “clean-sheet” development process to ensure that the correct achievements were made in the areas of efficiency, driving pleasure, technology, and emotions. BMW Vision EfficientDynamics is the most comprehensive implementation of the EfficientDynamics philosophy seen to date.
Base Performance and efficiency details
The powertrain provides an electronically limited top speed of 155 mph, with acceleration to 60 in a touch over 4.5 seconds. Average fuel consumption in the EU test cycle is 62.6 mpgUS on the NEDC. CO2 emission reduction is even more outstanding when driving in the all-electric mode after charging the battery from a 120V plug.
Taking all emissions in the generation of electricity into account, the car’s emission rating is just 50 grams per kilometer and 125 + mpgUS.
The power and performance are made possible by combining a fuel-efficient 1.5L, 3-cylinder turbodiesel with an electric motor on each axle. The intelligent combination of these units enhances the dynamic performance and efficiency of the car. Overall system output is 356 HP and peak torque of 590 lb-ft. The special arrangement of the two motors and diesel engine allows all-wheel drive when drive in all-electric mode. The result is minimum power loss and transmission of the power available under all conditions.
Turbodiesel with unprecedented specific output
The smallish 1.5L turbo-diesel engine follows the downsizing principle of using a relatively small engine combined with a turbocharger to reduce fuel consumption.
Through its compact dimensions, the 3-cylinder fits conveniently in front of the rear axle like in an agile mid-engine sports car. Fuel is injected by the latest generation of Piezo-electric Direct Injection, and the turbocharger features variable intake geometry for maximum efficiency. Engine output from the 1.5L alone is an amazing 163 HP with peak torque of 214 lb-ft.
The specific output of 109 HP/L sets a new benchmark in diesel technology. The power delivered by the turbodiesel is conveyed to the rear axle by means of a double-clutch transmission (DCT). The advanced transmission technology allows the driver to shift gears without the slightest interruption of power. BMW Vision EfficientDynamics features a newly-developed version of BMW’s DCT with six speeds for maximum efficiency and flexibility.
Two electric motors make the Vision a full-AWD hybrid
The combustion engine is supplemented by two electric motors. Following the principle of “Best of Hybrid,” choosing the optimum combination of a hybrid synchronous motor on the front axle and a full-hybrid system at the rear allows for both performance and efficiency never before seen in a Hybrid from any manufacturer to date.
In this concept, the driver benefits from the efficiency of the electric motors over a far wider speed range than with a conventional hybrid car. The rear axle comes with a second-generation full-hybrid system corresponding to the technology in the BMW ActiveHybrid 7 production model. The compact electric motor positioned between the diesel engine and the DCT outputs a consistent 33 HP and is able to reach a peak of up to 51 HP. Maximum torque for the rear electric motor is 214 lb-ft, either supporting the diesel engine or in all-electric motoring. When coasting or applying the brakes, the electric motor acts as a generator and feeds electric power to the Li-Polymer battery in the car. The electric energy developed in this way is therefore captured without any additional consumption of fuel through the principle of Regenerative braking.
A second electric motor acts on the front axle. This engine, a hybrid synchronous motor, offers continuous output of 80 HP and peak torque of 162 lb-ft. An additional 112HP is available for a period of up to 30 seconds, and, for a 10-second “burst,” the electric motor is able to develop 139 HP. The power is transmitted through a 2-stage, single-speed reduction gearbox.
The BMW Vision EfficientDynamics is able to run completely under electric power, with the power of the turbodiesel engine alone, or through an infinite combination of all the three power sources. Depending on driving conditions, the two electric motors may be used both for accelerating and regenerative braking when applying the brakes and while coasting. This principle ensures efficient energy management, with the charge status of the LiPO battery constantly remaining within the optimum range. When accelerating, the electric motors help to boost the car for even greater performance, ensuring immediate response and a significant reduction in fuel consumption. For a short time, the cumulative maximum output of all three engines increases to 356 hp, with maximum torque generated by the three engines reaching 590 lb-ft.
The battery cells featured in BMW Vision EfficientDynamics are housed in a chassis element running from front to rear through the middle of the car similar to the EV1/Volt. The front unit is the lithium-polymer complex, an ongoing development of the lithium-ion battery. Overall, BMW Vision EfficientDynamics comes with a total of 98 lithium-polymer cells, each offering a capacity of 30 amp/hours and developing continuous output of 600 Amps at a voltage of 3.7 V. For a period of 30 seconds, each cell is even able to develop maximum output of 1,200 Amps.
Serial arrangement of the lithium-polymer cells serves to generate nominal voltage of 364 volts with total storage capacity of 10.8 kWh. Using an unusually high Depth of Discharge of 80 percent, the battery delivers 8.6 kWh. This superior performance comes on overall weight of the entire energy storage system of just 187 lb! A further advantage is that through the packs optimized dimensions, the LiPO cells together with an advanced operating strategy reduces the thermal load on the battery to such an extent that there is no need for active cooling
Convenient charging of the battery from a conventional outlet.
Regenerative braking is one source to replenish the LiPO pack but the best option is to connect the LiPO cells directly to a conventional outlet. Connected to a standard outlet (120 V, 10 Amp), the system requires a maximum of 7 hours to fully charge the LiPO pack. Wherever a higher voltage and amperage source is available (440 V, 30 Amps), a full charge can be completed is less than 45-minutes.
In addition to electrical energy storage, the BMW Vision comes with a conventional fuel tank at the rear end of the central chassis tunnel, offering a capacity of 6.6 gallons. Running on diesel fuel alone, BMW Vision EfficientDynamics is able to cover a distance of approximately 400 miles on the turbo-diesel engine alone. Benefitting from up to 31 miles in the all-electric mode, the car offers an overall range of approximately 430 miles.
As a result, this unique concept car offers all the requirements for using energy with maximum efficiency and at the same time experiencing the dynamic performance typical of BMW without any restriction of everyday driving qualities.
As a plug-in hybrid, the BMW Vision is able to cover the entire European, US EPA or Japan driving cycles without ever staring the Turbo-diesel engine. To determine the consumption of electric power, the only requirement is to compare the charge level of the battery before and after the test cycle. Applying this measurement process, the BMW Vision EfficientDynamics concept car consumes 28.2 kWh per 100 miles (282 Wh/mile), equal to a CO2 emission rating of just 50 grams per kilometer on the NEDC test cycles.
The BMW Vision differs from the principle of “form follows function” as is not just about the look of the car. Instead, it embraces every detail. Measuring 48.8" in height with an arch-like roofline, BMW Vision offers the slender silhouette of a classic Gran Turismo. With the combustion engine fitted in front of the rear axle, the designers have succeeded in giving the car a very low front end, with the flow of air being further smoothened by active louvers in front of the radiator, which close completely when the need for cooling air is low. This efficient function follows in the footsteps of the active air flap control already used as a feature of BMW EfficientDynamics in some of BMW’s current production models. As a further highlight, BMW Vision guides air smoothly and exactly as required into the car through an active air intake at the front.
Numerous details in the design including a number of body elements serve as air deflectors and guide vanes. Designed as ducts, for example, the A-pillars serve to channel the flow of air in the same way as the rear lights with their wing profile. The floor of the car is fully covered from front to rear and from one side to the other, thus maintaining a smooth surface to avoid any air swirl that would serve to increase fuel consumption. Slender openings around the front air dam guide the air into two closed ducts leading inside the front air dam to the wheel arches where the air comes out again through a very slim aperture at high speed next to the outer wheel flanks. This air jet rests on the front wheels like a curtain and is therefore referred to most appropriately as the “air curtain.” It provides a highly stabilizing effect.
Overall vehicle concept for a drag coefficient of just 0.22
To further optimize the aerodynamic qualities of the entire vehicle and keep rolling resistance to a minimum, the BMW Vision comes with tires and wheels of quite unusual size on a sports car. The tires measure 21-195/55 providing a contact surface on the road offered only by a much wider tire. In combination with the sophisticated axle geometry, this ensures excellent driving dynamics.
The extra-large wheel covers extending over part of the tire flanks add to the unique, very different look of BMW Vision from the side. The blade profile integrated in the wheels serves furthermore to reduce the negative effect of the turning wheels on the overall aerodynamics of the car. In all, these features optimizing the aerodynamic qualities of the car give the BMW Vision EfficientDynamics concept car a very low drag coefficient (Cd) of just 0.22.
Intelligent lightweight construction
In both exterior and interior design, the BMW Vision stands out. The chassis and suspension of BMW Vision are made completely of aluminum; while the roof and the outer door skins are made almost completely of polycarbonate glass that automatically darken as a function of the light shining on the car.
Measuring 181.1" in length, 74.8" in width and 48.8" in height, this unique concept car offers ample space for up to four passengers and their luggage. Thanks to the lightweight construction, curb weight is an astoundingly light 3,076 lb. In its power-to-weight ratio, the BMW Vision concept car is far superior to all other hybrid vehicles on the road today.
Of course it is LED all-around. LED lights at both the front and rear of the BMW Vision provide an innovative and distinctive look of the BMW standard, dual round headlights. The rear lights form part of the rear air deflector and merge completely into the rear contour.
3-dimensional Head-Up Display
The Heads-Up Display creates a powerful impression of three dimensions, at the same time providing the option to present various signals more in the front or more in the background, depending on their relevance and current driving conditions.
The Head-Up Display also projects information important to the driver on to the windscreen with the gauge graphics visible in the background while the latest information on route guidance or warning signals from BMW Night Vision are shown in the foreground.
Forward-looking energy management
With the on board systems being networked with one another, Data provided by the rain sensor or Active Cruise Control with its Stop & Go function as well as by the navigation system can be evaluated by the central control unit offering an overview of current and upcoming driving conditions. The on-board computer is then able to forecast driving conditions on the stretch of road immediately ahead, such calculations serving to prepare the car for upcoming requirements and make efficient use of the energy available through optimum operation of all systems.
Should the high-performance computer see that the driver is about to take the Interstate, the power used for running the cooling system is reduced for a certain period in advance on the assumption that the short increase in coolant temperature resulting from such an energy-saving measure will quickly be set off by the higher speed of the car. Another example of such pre-conditioning is the regeneration of energy from the air conditioning, from Electronic Power Steering and the Brake Assistant.
This is BMW’s version of the near future and with the performance of a supercar, the efficiency of an all-electric BEV and the range of a fuel miser, what is not to like?