2011 BMW ActiveHybrid 7 First Drive

Germany Discovers Electricity

Published: 10/30/2009  - by Alistair Weaver, VP of Editorial and Editor-in-Chief

There's nothing like having your bases covered. For some time now, BMW has been telling us that the real long-term clean energy solution will be the hydrogen-fueled internal combustion engine. But over the next couple of years, BMW will also introduce the Megacity, an all-electric car, as well as a two-mode hybrid version of the X6.

Now that BMW has discovered the ways of the electron, it is bringing us the first step along the road to cleaner energy with the 2011 BMW ActiveHybrid 7, which the techno-geeks will tell you is a mild hybrid.

As the first of BMW's new-wave propulsion systems to emerge, the ActiveHybrid 7's powertrain is the simplest, combining a small electric motor with the 4.4-liter V8 of the 7 Series. The ActiveHybrid 7 cannot be powered by its electric motor alone like a full hybrid. Instead the twin-turbo 4.4-liter V8 is designed to stop when you halt the car in traffic or at a stoplight and then the electric motor with its lithium-ion battery restarts the engine smoothly when you're ready to go again.

Of course GM has long offered this same hybrid strategy for many of its vehicles, while the European carmakers (notably Audi and Porsche) have recently turned to this technology for a quick-fix solution to the clean-air equation. The net result for the 2011 BMW ActiveHybrid 7, says BMW, is the performance of a V12 with the fuel consumption of a V6 — a feel-good solution for plutocrats in a hurry.

Germany Discovers Electricity
Let's not pretend that the 2011 BMW ActiveHybrid 7 is a truly eco-friendly alternative to the small car. Its rating for CO2 emissions on the European driving cycle is 219 g/km, more than double the 89 g/km rating of a Toyota Prius and roughly the same as a Porsche 911 Carrera. It might be a significant step forward from a 750i, which is rated at 266 g/km, but it's unlikely to gain a standing ovation at a tree-huggers' love-in. Let's remember that this is still a gargantuan sedan, measuring 205.2 inches overall and weighing 4,729 pounds when you choose the long-wheelbase version (a short-wheelbase ActiveHybrid 7 will be available, too).

Differentiate to first principles and the ActiveHybrid 7 is really a 750i with a twist. The twin-turbo, direct-injection, 4,395cc V8 is retained, but it's been retuned to develop 443 horsepower and 479 pound-feet of torque, while the standard 750i's V8 puts out 400 hp and 442 lb-ft of torque.

The new addition to the powertrain is an electric motor that sits between the engine and the torque converter of the eight-speed ZF transmission. Codeveloped with Daimler, this 51-pound motor is rated at 20 hp and 155 lb-ft of torque. If you add it all up (which you can here, because the electric motor is in series with the engine), you get a combined effort of 459 hp and 516 lb-ft of torque.

The electric motor gets its juice from a 120-volt battery of 35 lithium-ion cells that is mounted to the left-hand side of the trunk. It measures 14.6 inches by 8.7 inches by 9.1 inches, and the compact size of the battery is the only real magic in this hybrid system.

Just as with most other hybrid cars, the 2011 BMW ActiveHybrid 7 has regenerative brakes, so when you lift off the gas or apply the brakes, the small-capacity 0.4 kWh battery gets recharged. The location of the battery in the trunk does have a negative impact on the capacity of the (still mammoth) trunk, but BMW's engineers deemed it the best solution for crash safety and mass distribution. Overall, the hybrid 7 Series weighs just 130 pounds more than the standard 750i.

Mildly Hybriding
The ActiveHybrid 7 does not deliver a hybrid driving experience in the manner of a Toyota Prius or even this BMW's most obvious rival, the Lexus LS 600 h. The omnipresent operation of the V8 ensures that the basic experience is almost identical to any other gas-powered product of Bavaria. Indeed, you suspect that the plethora of dials and gizmos in the cabin are really there to remind those inside that they're riding in an alternative vehicle.

Our best advice is to ignore the power consumption meters and concentrate on the speedometer, because this 7 Series is comically quick. Luxury limos this big really have no right to hit 60 mph from rest in just 4.7 seconds. Lean on the throttle and the abundant urge of the twin-turbo V8 through the eight-speed transmission makes a mighty impression. Even above 100 mph on the autobahn, the ActiveHybrid keeps pulling and it scampers to its electronically limited top speed of 155 mph with effortless grace.

Some of the effect comes from the extra kick of the engine at peak rpm, even though the car has a taller final-drive ratio than a conventional 7 Series in order to maximize fuel economy.

Stop and Go
The only real novelty of driving the 2011 BMW ActiveHybrid 7 is the stop-start function. Pull to a stop with your foot on the brake and the engine will automatically stop, though the climate control and entertainment systems aren't affected and keep running because they're powered by the electronics system, not the engine. Release the brake and the V8 starts again. It's a familiar process, but it works exceptionally well here. There is something undeniable soothing about sitting in silence, we discovered.

BMW has yet to announce official fuel consumption figures for this car but is claiming a 15-17 percent improvement over a standard 750i. Over the test route of mixed autobahn and rural roads that we drove in Germany, we achieved a respectable (but hardly green) 19.7 mpg.

The ride and handling is unaffected by the green technology. The car's 50:50 weight distribution is retained and the extra mass makes scant difference in a car this big. As in the 750i, the car is supplemented by the electronic Dynamic Driving Control. This system allows you to toggle through four vehicle configurations — Comfort, Normal, Sport and Sport Plus. They comprise increasingly aggressive levels of damper control, steering assistance, antiroll bar stiffness, gearshift calibration, throttle gain and stability control. There is an appreciable difference between the settings of this quartet of modes, but the technology still feels slightly superfluous. Most drivers would be best advised to select Normal and forget about it.

For a luxo-barge, the 7 Series does a fine job of posing as a sport sedan. It's not as nimble as a 5 Series, of course, and you're always aware of its bulk, but it remains true to BMW's principles. The steering has more weight and feel than a Mercedes S-Class and fine body control is matched by a cosseting ride. This is still the driver's limo, even though the S-Class still has marginally better overall refinement.

Electrons Are Our Friends
The price for the 2011 BMW ActiveHybrid 7 has yet to be announced, but BMW North America is estimating a price of more than $100,000, a significant jump from the $80,455 price of a standard 750i. BMW is promising more standard equipment, though, and the exterior comes littered with ActiveHybrid badges to remind the world that you're a caring, sharing capitalist. BMW also expects this model to account for 10 percent of 7 Series sales in the U.S., a significant amount.

To be fair to BMW, it's not presenting this car as a solution to climate change. The 2011 BMW ActiveHybrid 7 is simply a means of retaining the performance and appeal of a top-end luxury car, whilst taking a slightly lower toll on the world's resources. Any technology that makes it slightly more practical or politically correct to drive a car as exciting as a BMW 7 Series should be hailed as a success.

The manufacturer provided Edmunds this vehicle for the purposes of evaluation.