BMW Concept 7 Series ActiveHybrid
By Kevin Miller
Just as Mercedes-Benz introduced its S 400 BlueHYBRID last week, now BMW has released details about its compound-word-named hybrid large luxury sedan, though BMW’s vehicle is only a concept at this point. The Concept 7 Series ActiveHybrid comes with a turbocharged V8 gasoline engine and electric drive as a mild hybrid concept. The drivetrain technology featured in the concept car allows enhanced driving dynamics together with a reduction of fuel consumption and emissions by about 15 percent (in the EU test cycle) compared to the same car running on a combustion engine only.
The drivetrain of the BMW Concept 7 Series ActiveHybrid is made up of a V8 gasoline engine with Twin Turbo and High Precision Injection based on the power unit of the BMW 750i. Maximum output of the conventional engine in the regular production model is 407 hp, with peak torque of 442 lb-ft. This engine is combined with an electric motor fully integrated in the transmission housing, developing maximum output of 20 hp and peak torque of 155 lb-ft.
As in the Mercedes-Benz S 400 BlueHYBRID, the electric motor integrated in the transmission housing replaces the starter as well as the conventional alternator driven by the engine. Electrical energy is generated through brake energy regeneration. Integrated power electronics control the flow of electrons to and from the motor/generator. A high-performance lithium-ion battery integrated in the luggage compartment of the 7 Series Concept stores the energy generated and supplies power to the on-board electrical circuitry.
If you read last week’s article about the Mercedes-Benz S 400 BlueHYBRID, the details of this hybrid BMW concept are probably sounding a bit familiar. That is because the hybrid system components are the same in both cars. BMW and Daimler are cooperating in a joint venture for engineering hybrid drive system components. In this joint venture the two manufacturers have developed components for hybrid drive such as power electronics and high-voltage batteries. The objective of this joint venture is to develop and test components for hybrid drive in upmarket vehicles, each manufacturer then integrating the hybrid components developed into their respective cars in accordance with the individual philosophy of each brand.
Like the Mercedes, the BMW Concept 7 Series ActiveHybrid features start-stop technology for the internal combustion engine and a 120 V power network which is parallel to the “regular” 12 V vehicle electrical system. This electrical system ensures optimum comfort for passengers whether or not the gasoline engine is running, by running such accessories as the air conditioning compressor and ventilation fan from the battery.
There are subtle visual cues which differentiate the Concept 7 Series ActiveHybrid from thirstier 7-series sedans. One of these is an aluminum band stretching across the entire width of the front end beneath the license plate, which provides a more aerodynamic face to the vehicle. The lower air intake scoop is covered in the middle by this aluminum band, and the openings to the left and right reﬂect the contours of the headlights which are above. The foglamps are located at the extreme edge of the air intake openings, and each house seven LED light units. Matching aluminum air guidance elements and exhaust tailpipes adorn the rear of the car.
BMW’s press release about this concept was nineteen pages long, but most of those pages were filled with wordy, repetitive paragraphs about the basics of the mild hybrid system and BMW’s Efficient Dynamics philosophy. Pretty much all of the technical information from the press release has been summarized in the paragraphs above. Unfortunately, nowhere amidst the clunky prose did the press release contain any quantitative fuel economy numbers or performance figures, nor were on-sale dates announced or tentative pricing mentioned. The lack of these facts makes it appear that Mercedes is going to beat BMW to market in the full-size European luxury sedan segment.
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