As BMW proliferates its EfficientDynamics hybrid technology throughout its lineup, the next logical choice to receive the treatment has long been the 5-series, of which a new model has just debuted. The long-rumored 5-series ActiveHybrid finally steps into the limelight in Geneva.
Early rumors of a hybrid 5-series went only so far as to place an existing BMW EfficientDynamics hybrid powertrain under the hood and leave it at that. BMW is not so lazy as that and has instead bestowed upon the 5-series its own unique hybrid drivetrain, albeit one based on existing EfficientDynamics technology and one that will likely filter down into other models in the future.
The key differentiator for the 5-series ActiveHybrid is the choice of internal combustion, which is the smallest yet in the ActiveHybrid family. Rather than the 7-series' ActiveHybrid's V-12 or the X6 ActiveHybrid's twin-turbo V-8, BMW thought smaller and instead chose their latest inline-six motor, the N55 single-turbo, direct-injected 3.0-liter mill that makes 300 horsepower and 300 pound-feet of torque in the non-hybrid 535i.
In the ActiveHybrid model, the inline-six is matched to an eight-speed automatic transmission, just like on the 535i, only this time with a 40kW electric motor sandwiched between them. Connected to the gasoline engine by an automated clutch, the electric motor can move the car by itself, boost the gasoline engine's performance or act as a generator to recover braking energy. Though Regenerative Braking is not new to BMWs, the company claims that the 5-series ActiveHybrid's system is far more powerful than any other in its fleet.
Power for the electric motor comes from a battery mounted in the rear of the car near the rear axle, both to keep it safe in accidents and to optimize weight distribution. Not only does this battery supply power to the electric motor, but it also powers all of the car's onboard electronics as well as the climate control system so that the interior temperature can be maintained even when the gasoline engine isn't running. To minimize battery drain, all of the car's electrical systems are networked together so that the central computer can optimize power flow to all components.
That's not all the computer can do. It also has a start/stop feature so that it can shut down the gasoline engine and run on electric power to conserve gas. What's more, it takes constant input from all of the vehicle's sensors as well as the navigation system and uses the data to attempt to predict upcoming road conditions and prepare the car's systems for them in advance. To top it off, the car will also monitor your route and, if the battery is fully charged, shut off the gasoline engine early and proceed on the last leg of your journey on electric power only, extending the car's electric-only range by 30 percent.
Visually, there is little to differentiate the ActiveHybrid from a standard 535i, ignoring the oversized EfficientDynamics stickers on the sides. Propeller-like five-spoke wheels make this car easier to pick out on a dealer lot, and eagle-eyed readers will notice that the lower front fascia has been revised with a new horizontal bar and LED fog lights. Beyond these minor changes, the body is otherwise the same as a 535i.
Taken together, BMW says its bag of tricks has resulted in a 10-percent decrease in both emissions and fuel consumption. More than that, the company says it has boosted both city and highway fuel economy significantly as well as increased the car's electric power-only range. Unfortunately, the company hasn't released any solid numbers yet, so you'll just have to tune into our complete live coverage of the 2010 Geneva Motor Show next week to find out, where the 5-series ActiveHybrid will keep the 5-series Touring company on the BMW stand.