The BMW Vision EfficientDynamics Concept is designed and billed as the ultimate expression of BMW's emerging strategy. The Vision features seemingly every high-tech, lightweight, and aerodynamic trick the company has developed in an all-out effort to improve efficiency. And of course, BMW also says the Vision is designed to deliver an exhilarating driving experience. The end result is a lightweight, 2+2 coupe powered by a plug-in hybrid drivetrain that BMW says develops a total output of 356 horsepower.
One look at the Vision and its clear BMW has created a vehicle that goes way beyond today's hybrid. Case it point, the exterior, which employs advanced layering technology to layer the various pieces of the Vision's bodywork over each other. The process smooths out joints and seams and help to reduce the number of overall components. The wild bits and pieces jutting off the car are all there for a reason. At the front, the A-pillars are designed to guide air around the greenhouse where a wrap-around spoiler, fin-like rear fenders and blade-like taillights all duct the airflow off the back of the car to in an effort to further minimize turbulence and drag.
The aerodynamic tricks aren't limited to obvious body modifications, either. Underneath, the entire underbody of the car is smooth and flat to minimize drag. Up front, active louvers in the fascia close when the airflow to the radiator isn't needed, streamlining the front of the car. Below them, small ducts in the air dam direct air through special passageways and out into the front wheel wells, creating a high-velocity curtain of air over the front wheels that BMW says aids stability.
The wheels themselves are also designed for aerodynamics with the profiles of the individual spokes designed to cut cleanly through the air and, again, minimize turbulence and drag. Despite their massive size, the wheels are wrapped in 195/55 narrow, low-profile tires to minimize rolling resistance. To keep the handling sporty, they're wrapped around 21-in. wheels that help give the tires a larger contact patch, one that is longer than it is wide for minimal wind resistance. All told, the Vision slips through the air with only a 0.22 coefficient of drag, significantly better than the 2010 Toyota Prius' 0.25.
Taking advantage of the bodywork's aerodynamic tricks is a powertrain designed to be as powerful as it is efficient. The Vision's unique hybrid drivetrain can act as either a parallel or series hybrid depending on driving conditions. A 1.5L turbocharged three-cylinder diesel engine is mounted behind the rear seats and connected to a six-speed, dual-clutch transmission driving the rear wheels. A total of two electric motors are also employed, one sandwiched between the diesel engine and the transmission and one mounted in front driving the front wheels.
On the road, the Vision can be propelled by the diesel engine itself, by the two electric motors alone or by a combination of both. The diesel engine can drive the rear axle by itself, can be supplemented by the electric motors or can run independently to recharge the car's batteries or supply power to the electric motors to move the car.
The diesel engine by itself develops 163 hp and 214 lb-ft of torque while the rear electric motor normally generates 33 hp and 214 lb-ft and the front electric motor generates 80 hp and 162 lb-ft. When more power is needed for acceleration and passing, both electric motors can be called on to boost output. The rear electric motor can temporarily increase its output to 51 hp while the front electric motor can boost power to 112 hp in 30-second bursts or 139 hp in 10-second bursts. Combined, all three motors create 356 hp and 590 lb-ft of torque, according to the automaker. BMW says its enough to rocket the Vision to 62 mph in 4.8 sec and hit an electronically-limited top speed of 155 mph, all the while getting 62.6 mpg average on the European cycle and emitting only 99 grams per kilometer of CO2, or 0.35 lbs per mile.
Powering the Vision's electric motors is an advanced Lithium-Polymer battery mounted in the center tunnel of the car between the seats. It contains 98 battery cells rated at 30 amp/hours each. Total output is 600 amps at 3.7 volts, but when called on, each cell can produce 1200 amps for up to 30 seconds and the battery can reach a nominal 364 volts, BMW says. Total battery storage is 10.8 kilowatt-hours and the Lithium-Polymer chemistry will allow the battery to be safely drained to just 20% of capacity, giving the car 8.6 kilowatt-hours of usable driving power. That translates to a 31-mile range on electric power only. Combined with the 6.6-gallon diesel tank, the Vision's total range is an impressive 431 miles.
Thanks to the higher currents used in European countries, the Vision can be plugged into a standard 220-volt, 16-amp European outlet and be fully-charged in just two and a half hours. If a more-powerful 380-volt, 32-amp plug is available, it can be charged in just 44 minutes. Careful thermal management of the battery cells means that no cooling system for the battery is required -- a development BMW says keeps the weight down to just 187 lbs.
Weight, of course, is the biggest enemy of both performance and efficiency. To combat it, BMW employed a number of weight-saving tricks and exotic materials. The entire chassis is made of aluminum, as are all of the suspension components. The body panels are made of composites while the roof and doors are almost entirely composed of polycarbonate glass, making them transparent. A technology that has been employed on eyeglasses for some time, the technology automatically darkens the material when light is shined on it. A structural bar running through the door doubles as both an armrest and reinforcement to protect the occupants in the event of a side-impact accident.
To further reduce weight and increase aerodynamic efficiency, the Vision uses a minimal footprint and cross-section. At 180.1-inches long, it's the same length as a 3-Series, but at 74.8-inches wide and just 48.8-inches tall, its four inches narrower and 10 inches shorter. The end result of BMW's weight and size restrictions is a car that tips the scales at just 3076 lbs.
The compact size, of course, takes its toll on passenger and cargo space. The Vision's cargo area is just 5.3 cubic-feet, enough for two small golf bags. Drop the rear seats, though, and you can pick up a bit more space for luggage. To make up for the overall lack of size and subsequent lack of interior space, BMW has gone with a minimalist interior to keep weight down as well as maximize passenger room. Like the X6, there is no middle seat in the back, giving rear-seat passengers a bit more room around the tunnel housing the battery. The dash is padded only as needed to protect the front-seat passengers and cover up the mechanical bits while the seats are made from a simple backbone and a Kevlar shell to minimize weight. Again, BMW's layering technique is used to keep interior components as simple and smooth as possible.
Getting into the Vision promises to be simple as well. The doors are hinged on the A-pillar and open much like those on the Mercedes-Benz SLR McLaren. The wide openings and lack of B-pillars make entry and egress to both the front and rear seats easy as well as allow easy access to the rear cargo area.
Skeptics may note that lightweight materials and hybrid drivetrains aren't anything new, and for them, BMW has a few more tricks up its sleeve. LED headlights and taillights save energy while the taillights can shift from red to yellow when the turn signals are activated. The Vision also comes loaded with top-of-the-line technology including satellite navigation, Active Cruise Control with Stop & Go and BMW Night Vision. While impressive, these technologies still aren't anything new. It's how they're combined that is.
First, the cockpit of the Vision features a 3-D heads-up display that not only projects information from the gauges but also includes information from the navigation system, vehicle alerts and information and warnings from BMW's Night Vision technology. Thanks to the 3-D projection, the system can move the various pieces of information around, putting, say, the navigation in the foreground and the gauges in the background. Even better, the system is customizable so you can tailor it to the information you access the most.
What may be even more impressive, though, is the central computer. Linked to every system in the car, the computer continuously monitors driving conditions and inputs and attempts to predict the road ahead. Using information from the navigation system, brakes, throttle, Active Cruise Control, automatic wipers and headlights and more, the system tries to predict how the drivetrain will be called upon next and adapt energy usage accordingly. For example, if the computer believes that the driver is about to turn onto a freeway, it may reduce power to the engine cooling system and divert it elsewhere in anticipation of the higher airflow at higher speeds. These constant adjustments to power output -- whether to the drivetrain, accessories or other systems -- maximizes energy use and efficiency, wringing every last mile out of diesel fuel and electrical power onboard.
Impressive as the Vision EfficientDynamics concept may be on its own, it remains to be seen how many of its features are actually production-viable. Stay tuned for more on the BMW Vision EfficientDynamics concept and the future of BMW hybrid and alternative drivetrains when the concept debuts at the 2009 Frankfurt Motor Show on September 15 and 16.
BMW Vision EfficientDynamics Concept
Vehicle layout Mid-engine, AWD, 4-pass, 2-door, coupe
Engine 1.5L/163-hp/214-lb-ft turbodiesel, plus 139-hp/162-lb-ft front and 51-hp/214-lb-ft rear electric motors
Transmission 6-speed twin-clutch auto
Curb weight 3100 lb (mfr)
Wheelbase 78.8 in
Length x width x height 181.1 x 74.8 x 48.8 in
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| bmw vision efficientdynamics concept |
bmw vision efficientdynamics concept
bmw vision efficientdynamics concept
bmw vision efficientdynamics concept
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