Video: BMW’s Vision EfficientDynamics turbodiesel plug-in hybrid concept

p90047138_highres-1280After several months of speculation and official teases for the past week, all the details on the Vision EfficientDynamics Concept that BMW will show at the Frankfurt Motor Show in a couple of weeks have been revealed. The speculation about the concept’s powertrain has gone in several directions, almost all of which were correct. The new concept is a plug-in hybrid with a three-cylinder turbo-diesel engine. Conceived with the idea of melding the performance of a M3 with exceptionally low fuel consumption, BMW claims a 0-62 mph time of 4.8 seconds while scoring 62.6 mpg (U.S.) on the E.U. combined test cycle.

There has been considerable speculation that future BMWs will go to smaller engines including a three-cylinder. The concept uses a 1.5-liter turbodiesel that is essentially half of the fabulous 3.0-liter found in the 335d. The triple is rated at a hefty 163 hp with peak torque of 214 lb-ft. The engine is paired with a six-speed DCT derived from the unit used in the M3 and Z4.

Adding fuel to recent reports that BMW would not continue developing the two-mode hybrid system that will debut soon in the X6, the concept uses a new strong hybrid system. The new system is a further development of the mild hybrid that is debuting in the ActiveHybrid 7. As in the 7, a more powerful 33-hp electric motor is sandwiched between the engine and transmission. A second 80-hp motor provides drive to the front axle. The total net output of the drive system is 356 hp and 590 lb-ft of torque.

Making use of electric motors requires some electrical energy system. Here BMW’s new concept has an arrangement similar to the Chevrolet Volt using a lithium-polymer battery pack running down the center tunnel of the car. Also similar to the Volt, the pack has a usable capacity of 8.6 kWh. However, the total capacity is just 10.8 kWh. BMW claims the pack used in the concept can use 80% of its capacity, considerably more than the 50% that the Volt uses. The upside is that the pack weighs just 187 pounds. When plugged into a standard European 220 V / 16 A outlet, the battery can be charged in just 2.5 hours.

Unlike the Volt, which is designed to give its full performance from the electric drive system, the BMW concept gets its full capability from the blended power delivery. The concept is able to run about 31 miles on electricity alone and complete the NEDC test procedure on electricity. The efficiency of the diesel engine means that the 6.6-gallon tank can propel the car another 400 miles. The electrical energy consumption of the concept is 28.16 kWh/100 miles, which compares to the claimed 25 kWh/100 miles for the Volt.

Another area where the BMW differs, particularly from the original Volt concept, is aerodynamics. The Volt is well known for having had terrible drag properties. The BMW is claimed to have a drag coefficient of 0.22, part of which was attained by moving the diesel engine to the back of the car. The mid-mounted engine sits just ahead of the rear axle, which combines with the small front electric motor for a very low front end. Similar to the Cadillac Provoq concept – which eventually became the production SRX – front air resistance is reduced by using thermostatically controlled slats ahead of the radiator inlets to redirect air when it isn’t needed for cooling. Overall, BMW says it has made use of knowledge gained from motorsports in optimizing the aerodynamics of the Vision EfficientDynamics concept.

Beyond the powertrain, BMW has implemented an array of technologies to optimize the concept. A full aluminum chassis and suspension along with a roof and much of the skin made from a light-sensitive polycarbonate combine for a claimed mass of just 3,076 pounds. Other interesting design tidbits include polycarbonate glass that gets darker when light shines on it, and LED lighting all around has given the designers more freedom as well as reduced energy consumption.

Perhaps most interesting is what BMW refers to as “Forward looking energy management.” The idea here is to utilize the other systems in the vehicle to anticipate what is coming and optimize the use of the various powertrain elements to cut energy use overall. For example, the radar sensor for the active cruise control could be used to switch off the engine preemptively and trigger regenerative braking if traffic ahead is slowing down. We’ll be “looking forward” to learning more about this system.
Source: Autoblog

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