Miami, Florida -- BMW has a problem: the swanky South Beach clientele who love their impractical $80,000 four-seat trucks (you know, the ones with the 400-hp twin-turbo V-8) may one day start caring about fuel economy. They might have a diesel-powered X5 in their polished marble driveway if practicality weren’t so gosh-darned unappealing.
Enter the ActiveHybrid X6, a big solution to the big dilemma of suddenly environmentally conscious nouveaux riches. We’re using the word “big” because the idea of a BMW hybrid has a big problem: all of the drawbacks of a full-blown hybrid system (the lack of progressive brake feel, the artificial electric power steering, and the lack of discrete gear ratios) directly attack the Ultimate Driving Machine virtues that have made BMW so successful.
But notice we also used the word “solution.” Problem solved -- the Toyota Priuses of the world no longer have an excuse to drive like numb, computer-controlled appliances. The X6 proves that, thanks to some creative engineering, hybrids don’t have to be less involving.
First of all, the X6 uses the two-mode transmission that it codeveloped with GM, Chrysler, and Mercedes-Benz. Like the other vehicles that use this transmission design, the X6’s gearbox offers four fixed gears and two ranges of CVT operation. But unlike the GM and Chrysler applications, which switch back and forth between CVT and fixed gears, BMW has programmed the transmission to pretend it’s a conventional seven-speed automatic. It shifts through seven fixed ratios that never change -- even though all of the even-numbered “gears” are actually created by keeping the CVT at a constant ratio. (The transmission uses an eighth ratio, but only for coasting.)
BMW’s second trick is to eliminate the strange pedal feel as the braking system apportions declarative duties between the electric motor and the brake pads. To this end, the X6 uses a fully by-wire system, meaning the brake pedal is just an electric switch. It had us completely fooled -- it feels absolutely no different from any other BMW brake pedal, and easily gives the X6 the best brake feel of any hybrid on the road.
The X6 will switch off the V-8 at speeds up to 36 mph, and can travel up to 2.5 miles on electric power alone. The system is very willing to keep the gas engine switched off in city traffic, and the result is an enormous gain in fuel economy. The EPA highway rating climbs 1 mpg to 19, but the city rating jumps from 13 mpg to 17, a tremendous 30-percent improvement.
There are a few drawbacks, of course: the electronics module on top of the V-8 requires a bulge in the hood that makes the X6 look in desperate need of a nose job. The hybrid system adds weight to an already obese vehicle; pushing the ActiveHybrid X6’s weight to 5688 lb. Perhaps that’s now too much weight for the suspension, as the hybrid X6’s ride is slightly harsh and bouncy.
The battery back is located beneath the cargo load floor, space usually taken up by the torque-vectoring rear differential -- so the hybrid X6 uses a conventional open diff. It is also equipped with smaller, skinnier tires, so at-the-limit handling will likely suffer, but we haven’t seen too many X6s at the track.
This X6’s fuel economy boost comes at almost no cost to its spectacular straight-line performance, as the incremental mass is nixed by the additional thrust of the electric motors—the engine produces 400 hp and 450 lb-ft of torque; total system power is 480 hp and 575 lb-ft of torque. BMW says 0-60 mph is identical to the regular X6 xDrive50i, which we clocked at 5.1 seconds.
Of course, the diesel-powered X5 produces far greater EPA numbers both in the city and on the highway (19 and 26 mpg, respectively), but it certainly can’t sling itself to 60 mph in five seconds. While the diesel might have been a much simpler and more economical solution for the X6, too, nothing says “I now care about the environment” like a hybrid badge. Especially when you’re beating on sports cars at the stoplight drags.