BMW corporate enthusiasm has been electrified by the announcement of its new zero-missions, battery-powered Bimmer brand – the Megacity urban car due in a few years – but in the meantime it’s been generating marketing sparks with a pair of hybrid lightning bolts.
Its current efforts to apply the electric flux are being realized through the drivetrains of the over-the-top potent, preposterously weighty, preternaturally complex and pretty darned pricey at $99,900 ActiveHybrid X6 we’ll look at here and the new ActiveHybrid 7 sedan – now the world’s most powerful hybrids. Think of them as BMW’s effort to save the planet, one 480-hp hybrid sport-ute and one 455-hp hybrid luxury sedan at a time.
The X6 Sports Activity Coupe – as christened by BMW to differentiate it from its more practical family values luxury crossovers – was already a technology packed hot performer, particularly in 555-hp X6 M form, but the only hint of “green” associated with it was perhaps in the window tint.
The ActiveHybrid X6 actually lets buyers lay claim to a higher degree of environmental consciousness – while still allowing them to accelerating to 100 km/h in less than six seconds.
Producing and distributing this level of potency hybrid style, however, involved adding an entirely new layer of gee-whiz-grade technological complexity. Weight also went up a couple of hundred kilograms over its line-mates and, at 2,580 kg, is now getting scarily close to three old-style tonnes.
Balancing this is a claimed mileage improvement of some 20 per cent.
The ActiveHybrid X6 fuel usage ratings are 12.6 litres/100 km city and 10.3 highway, compared to the six-cylinder X6’s 14.4 city/10.0 highway, and eclipse the 17/11 plus of the 5.0i and M. After a week of intercity-highway speed cruising, around-town errand running and some back roading, the on-board readout showed an average of 12.1 L/100 km.
It accomplishes this impressive feat by combining its gasoline-fuelled V-8 with a pair of electric motors and a unique transmission.
The V-8 is a 4.4-litre, twin-cam, direct-injection unit fitted with twin-turbos that makes 400 hp and 450 lb-ft of torque. The electric motors are rated at 86 hp and 91 hp and, when everything’s working together, the total combined output climbs to that magic 480-hp figure, along with a prodigious 575 lb-ft of torque.
This gets to the xDrive all-wheel-drive system via a complex, electronically controlled ,continuously variable transmission incorporating three planetary gear sets and multiple clutches working in combination with the twin electric motors to provide seven gear rations. And, oh yes, it has dual modes, one for stop-and-go traffic conditions and the second to optimize higher-speed operation.
When moving off and at low speeds, one electric motor provides propulsion and the X6 can operate at up to 60 km/h for 2.5 km or so in this mode. But as soon as power requirements go up, the second motor starts the V-8 and then acts as a generator to supply the X6’s electrical requirements. A regenerative braking system helps top up the nickel-metal-hydride battery pack.
When full power is called for, such as a driver-generated “kick-down” to pass, the motors both add their output, and they take some of the load of the V-8 during cruising to improve fuel economy.
Even when stopped with the engine not running, or when running on pure electric power, all vehicle systems, including the electric air conditioner compressor, continue to operate as normal in any temperature.
When you climb in and press the start button in the morning, you’re greeted by very un-hybrid-like V-8 idle sounds as it warms up to operating temperature. Moving off from a stoplight, you can feel the motor kick in, mainly because you’re anticipating it, which you don’t after a while. Despite the complexity of the driveline, it operates effectively, generally providing the response you expect in most situations.
With a very light foot on the throttle, I managed to get this big vehicle to ghost along almost silently for almost two kilometres of village street and back road. But stand on the pedal and it gathers itself up and runs impressively hard up to 100 km/h.
BMW’s X6 arrived for 2008 as more or less an X5 clad in outsized, coupe-like bodywork wrapped around four seats and a compact hatchback’s worth of cargo space.
It came in three flavours prior to the hybrid’s arrival for the 2010 model year, a base $63,900 xDrive 3.5i with twin-turbo, 300-hp, 3.0-litre-inline six, an $81,000 xDrive 5.0i with twin-turbo, 4.4-litre, 400-hp V-8 and the mighty M with a 555-hp, twin-turbo, 4.4 litre V-8 priced at $99,900.
The vehicle reviewed here was a 2010 but the 2011 versions on sale now are essentially unchanged in spec or pricing. All X6s are equipped with a lengthy list of equipment that on this one raised the total to $108,150.
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