What is it?
This is the BMW ActiveHybrid X6, and before we go any further let’s get the disappointment out of the way. Like the ActiveHybrid 7-series we drove last week, it won’t be coming to the UK because Brits like diesels too much. In the US, however, oil-burners are hard to shift, which explains why the new hybrid BMWs exist.
Under the bonnet, which is differentiated from standard versions of the X6 by a bulge necessitated by a power electronics package, sits a modified version of the X6 xDrive50i’s twin-turbocharged, 4.4-litre V8 petrol engine delivering 402bhp and 442lb ft of torque.
It is supported by a pair of electric motors mounted within the gearbox housing; the first has 91bhp and 192lb ft, while the second introduces a further 86bhp and 206lb ft.
What’s it like?
Given the complexity of the technology the car uses, driving the ActiveHybrid X6 is relatively straightforward. Climb up into the broad driver’s seat, slot the key into the ignition, press the dashboard-mounted starter button and… well, nothing happens. Well, nothing except the faint whirr of electricity powering up various systems, including the air-con compressor.
With sufficient charge held by the battery, the petrol engine remains idled. Draw the gear selector back, release the brake and with a gentle nudge of the throttle the X6 gracefully glides away, with only the rumble of the broad tyres providing any interruption to the otherwise eerie silence that you’ll get up to 37mph or a maximum distance of 1.6 miles.
It isn’t until the electrical charge of the battery is reduced, or you floor it with your right foot, that the petrol engine and the second of the electric motors are introduced into proceedings to boost performance.
Between the traffic lights along Miami’s ocean-front roads, where we tested the car, the ActiveHybrid X6 glided along in a hushed and unflappable manner, switching in and out of electric drive with impeccable efficiency.
At greater speed out along on Interstate 95, the introduction of the petrol engine on a continuous basis provided effortless in-gear performance at remarkably low revs, together with highly impressive levels of mechanical refinement.
BMW puts overall fuel consumption at 28.5mpg, but even on light throttle loads we had difficulty getting anywhere near it. The real-world figure, it seems, is somewhere closer to 22mpg, which sounds okay until you consider that the X6 xDrive35d sold in the UK is capable of 34mpg.
The hybrid architecture adds roughly 250kg to the kerb weight, taking it to a considerable 2450kg. However, the gain is all but offset by the extra reserves brought on by the electric drive, resulting in a power-to-weight ratio of 198bhp per tonne.
Although the claimed 0-62mph time of 5.6sec is fractionally slower than that of the X6 xDrive50i (5.4sec), subjectively the performance-enhancing qualities of the ActiveHybrid X6’s complex drive system are obvious in other ways.