BMW ActiveHybrid X6 Review

By Jonathan Spira on 17 February 2010
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One of the most remarkable things about the new BMW ActiveHybrid X6, besides its performance (0-60 in 5.4 seconds) and fuel economy (20% better than the standard X6),P90050144 is that the driver might never know he’s behind the wheel of a hybrid if it weren’t for the discreet ActiveHybrid badges and an electric drive display below the tachometer.

Indeed, the BMW ActiveHybrid X6 handles more like the X6 M than the standard X6, not to mention the run-of-the-mill hybrid.  This X6 may well be the most powerful hybrid in the world and yet the engine still shuts down at stops.  It is clearly no sluggish Toyota Prius but, weighing in at 5,765 pounds (some 496 more than the non-hybrid), it doesn’t promise the fuel economy of a Prius either.

We drove the ActiveHybrid X6 in a variety of conditions, P90050131from windy roads to city streets and it was easy to forget about the complex hybrid systems that contribute to its efficiency.    In fact, the transition between its gasoline and electric powerplants was seamless.

The new electric power steering was impressive: it provides exactly the type of feedback you would expect in a BMW (and not the disconnected feeling you get from most other hybrids).  Acceleration was equally impressive: the ActiveHybrid feels quicker than the standard X6 and this, in fact, is the car’s Achilles heel.  While most hybrid owners apply a fairly soft touch to the accelerator pedal, this car practically demands a lead foot.

The X6 has BMW’s powerful 400 hp twin-turbo V-8, a fairly efficient engine in its own right.  Add to that the high-performance electronics for the hybrid system (which explains the power dome on the hood since the box sits atop the engine),P90050138 a “power-split” transmission with two electric synchronous motors and three planetary gearsets, and a liquid-cooled nickel-metal battery capable of storing 2.4 KW hours of energy.  The power-split transmission acts as dual continuously-variable transmissions (CVTs), one for lower speeds and one for higher.  The two electric motors put out 91 and 86 horsepower, respectively.

All of this yields 480 hp and 575 pound-feet of torque, allowing the X6 ActiveHybrid to go from zero to 60 mph in 5.4 seconds while achieving 20% better fuel economy than the standard X6.

The X6 ActiveHybrid can run in all-electric or e-mode, with no CO2 emissions, at speeds of up to 60 km/h (37 mph).  In this mode, the ActiveHybrid is a zero-emissions vehicle. The V-8 engine is automatically and seamlessly engaged when needed.

The secret sauce behind the performance is the two-mode active transmission that supports enhanced efficiency or greater performance, as desired by the driver.  When the driver accelerates, the V-8 is joined by the two electric motors to provide additional power without increasing fuel consumption.  The motors also supply power in most driving conditions (such as highway driving), reducing the power output required of the V-8.

Since the battery pack is below the luggage compartment’s floor, no space is lost inside the vehicle, unlike with other gasoline-electric hybrids. P90053919 The battery charges when the driver applies the brakes or during deceleration; kinetic energy that would otherwise be lost is recovered by one or both of the electric motors acting as a generator, feeding electric power back into the battery.

The ActiveHybrid X6 keeps the driver apprised of the car’s operating status and efficiency in the instrument cluster but, unlike many other hybrids, the display is relatively low key and not a distraction to the driver.  A conventional tachometer displays the engine speed and an electric drive display shows the charge status of the battery pack, the regeneration status, and the electric motor operating status.  More detailed information is available on demand in the Central Information Display controlled by iDrive.

The only problem with this particular X6 is that the ActiveHybrid’s fuel economy (an estimated 17/19 mpg versus 19/26) and price make a great case in favor of the X5 xDrive35d.  The X5 diesel, albeit with less standard equipment, starts at $51,300 (and is currently eligible for the $4500 Eco Credit) while the ActiveHybrid X6, fairly loaded to begin with, starts at $88,900 (a mere $100 less than the cost of the X6 M).

2010 BMW ActiveHybrid X6
Base price/price-as-tested $88,900
Drivetrain Front engine, all-wheel drive
Engine 4.4/400 hp/turbocharged V-8
Transmission 7-speed automatic with Steptronic
Curb weight (lbs) 5765
Wheelbase (inches) 115.5
Length x width x height (inches) 192.1 x 78.1 x 66.5
0-60 mph (seconds) 5.4
Highway fuel economy (mpg) 19 (estimated)

The BMW ActiveHybrid X6

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