April 22 2010   Story: Bryan Joslin

Two years ago when BMW introduced the class-defying X6 as a “sport activity coupe,” it seemed pretty logical that the entire lineup of this off-beat but muscular vehicle would be driven by powerful turbocharged engines. Now the second-generation X5 — the vehicle on which the X6 is based — is receiving its mid-cycle refresh, and along with the usual minor cosmetic changes is also the beneficiary of a new engine lineup. For 2011, BMW’s venerable family hauler will abandon natural aspiration altogether, following its quirky stablemate’s path with a brace of new turbo engines.

The decision to go “all turbo, all the time" in the X5 isn’t so much about upping its performance image; it’s more a matter of maintaining the athletic reputation it has earned in its decade of existence while at the same time meeting new CAFE and emissions standards. Further assisting the turbo motors in achieving these new goals is a new automatic transmission and other efficiency gains, such as brake energy regeneration. Of course, it doesn’t hurt that the new boosted engines offer significant improvements in performance over their unboosted equivalents, as we recently discovered when we drove the new version for the first time.

The 2011 X5’s two new engines should be familiar to anyone following other new BMW models of late. The first is the 4.4-liter V8 with a pair of turbochargers resting the valley on top of the engine, breathing in a backwards manner, resulting in 400 horsepower and 450 lb-ft of torque. Explaining why it wears an “xDrive50i” suffix requires a BMW marketing manager’s finesse, but nevertheless it replaces the 350-hp, 350-lb-ft 4.8-liter xDrive48i in the X5 model lineup. This is the same engine as fitted to the X6 xDrive50i since its introduction, except that it’s mated to the new eight-speed automatic trans instead of the X6’s six-speed (though we expect that will also change for 2011). According to BMW, zero-to-60-mph times drop from 6.4 seconds in the old X5 V8 to an impressive 5.3 seconds. Fuel economy hasn’t been confirmed yet, but we’d be surprised if the combined EPA figure didn’t jump from 16 to 18 mpg or better. Unfortunately, we weren’t offered an X5 xDrive50i on our recent trip.

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We were, however, given the opportunity to sample what will certainly be the bread and butter of the X5 range, the xDrive35i variant. The former X5 xDrive30i, with its 3.0-liter natural-breathing inline-six, put out 260 hp and 225 lb-ft and could pull to 60 mph in 7.8 seconds. With turbocharging and the new tranny, the 2011 X5 can get there in 6.4 seconds, or roughly the same as the outgoing V8 version, thanks to 300 hp and 300 lb-ft under foot.

If you’re not paying attention, you may assume the same engine found in the X6 xDrive35i powers this model, but you’d be wrong. Building from the same basic architecture as the popular 3.0-liter twin-turbo N54 motor — the one found in the 135i, 335i, 535i and Z4 as well as the X6 — BMW lopped off the old twin-turbo cylinder head and replaced it with a new one that supports a single, twin-scroll compressor; the engineers then eliminated the throttle body and fitted Valvetronic induction for the first time ever on a turbo engine. The result looks remarkably similar on the dyno curve, but the new engine is more efficient and responsive. It’s also nine pounds lighter. The engine itself is said to be about eight percent more efficient than the twin-turbo unit, and combined with the new eight-speed transmission should take the X5 from 18 mpg to around 20 in combined driving.

Our first drive of the new powertrain was in the stop-and-go traffic of Miami and Fort Lauderdale. Not exactly Autobahn conditions, but entirely representative of the kind of driving most X5 owners will endure. The one exception was a brief off-road excursion in the Everglades, including four sill-deep, gator-inhabited water crossings. Not that our trip necessitated that, but hey, as long as we could, why not?

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Anyone who has spent time behind the wheel of an N54-equipped BMW knows what a joy that engine is to drive, and the N55 (as the single-turbo version is referred) won’t leave you wanting. In fact, the new engine actually behaves more like the outgoing V8. There’s no turbo lag from a dead stop and only the slightest hint on mashing the throttle when you’re already under way; the absence of turbocharger noise is almost spookier than the thought of driving into gator holes. The eight-speed automatic is flawlessly smooth, requiring visual confirmation from the tach to detect shifting action in normal mode. Sport mode is slightly more engaging (no pun intended) with more perceptible shifts in both directions, but highly refined and deliberate in everything it does.

Aside from the extra power and a couple of new overdrive gears, the driving dynamics of the X5 remain pretty much as they’ve always been — firm, precise and ready for just about any situation the road can throw its way. All-wheel-drive is standard on all X5 models, using the company’s rear-biased xDrive system that employs an electronically actuated center differential to apportion torque between the front and rear axles. The system forgoes heavy mechanical locking diffs, relying on wheel speed sensors to determine when a tire is losing traction. Although the X5 lacks serious off-road hardware such as a low range for the transmission, it is surprisingly capable off-road. BMW always seems willing to shock people with its billy-goat side, and this trip was no exception; we soon found ourselves rolling a brand-new X5 through numerous waist-high water crossings in gator country.

Part of any BMW facelift these days is a new set of bumpers and lights, and for 2011 the X5’s update is fairly mild. The most noticeable change to the face is bright-white LED corona lighting on the standardHID headlights, along with a repositioning of the foglights to a more inboard position. A matte-finished skidplate is also a dead giveaway to the new front end, which otherwise looks a bit more like X6. The theme continues in back with a matching skidplate in the rear bumper, recontoured exhaust openings, and updated taillight clusters with LED light bars within. BMW has abandoned most of the unpainted black trim for this go-around, leaving just the wheel arches and the lower sections of the bumpers naked.

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Inside, the changes are even milder. The basic configuration remains the same as the 2010 model, but the new fourth-generation iDrive unit is finally fitted, along with an 8.8-inch hi-res monitor in the center of the dashboard. The new iDrive is a welcome addition, with its added “jump” buttons for quickly changing between major functions. Optional side-view cameras and overhead viewing function offer improved visibility in parking situations, and are a welcome addition to any large-ish family vehicle.

With the new X5, BMW is also offering lane-departure warning and active cruise control, which includes a stop-and-go function. The lane departure system reads the boundaries of marked lanes and gives a gentle but distinct vibratory warning through the steering wheel. The system can be shut off, as we chose to do in the freeway traffic around the city. The advantage of active cruise control is that you can allow the vehicle to maintain one of four pre-set following distances, and it will obey all the way down to a stop. We chose the shortest setting for the congested traffic north of Miami and found the system to be exceptionally smooth in its operation, even though the distance was still a little conservative for our own preference. Off-road, we even used the system at low speeds, following our lead vehicle on the trail with no feet on the pedals. The only time it tripped up was when we crested a ridge and the approach of the road on descent triggered the brakes. The beauty of the BMW system is that the active functionality can be switched off in case you just wish to use conventional cruise control.

The overall changes to the X5 for 2011 are minor on the surface, with the changes underneath being of most significance. Most buyers in a BMW showroom won’t likely be able to distinguish between a 2010 and a 2011 without looking on the window sticker. Should they compare labels, however, they’ll not only be impressed with the improved EPA numbers, but also by the newer car’s lower base price. The 2011 X5 xDrive35i starts at $46,675 including destination charge, a full $1800 less than the outgoing xDrive30i model.

The turbo-powered X5 xDrive50i starts a little higher than its naturally-aspirated predecessor at $59,275, a $2100 premium for the additional power. The diesel-powered X5 xDrive35d — which currently accounts for roughly 30 percent of X5 sales in the US — will continue for 2011 with all of the same cosmetic and equipment updates as the rest of the range with a base price of $52,175. The 2011 X5 range will go on sale early this summer. As of now, a 2011 X5M has not been announced, but we’d be surprised if one wasn’t added before the end of this year.