The young, upscale buyers BMW is banking on to buy the new X3 are unlikely
to ever engage in serious off road adventures. No dummies, theyll realize
its based on the 3 Series, albeit a heavily modified 3 Series floorpan
and structure. Which means this SUVor SAV (Sports Activity Vehicle) as
BMW calls itis a crossover, and people who buy car-based SUVs are less
likely to take their vehicle way off roadif they can help it. If they
cant, the helpful Bavarian engineers have done their best to keep untoward
experiences to a minimum by equipping their crossover with a clever drive system
that keeps a firm grip on the road wherever it can.
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| The heart of the xDrive system is an electric motor that engages a multi-plate clutch pack and alters the front-to-rear torque split continuously based on need.
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xDrive
Those toga-clad angels in the BMW commercials have nothing to do with how xDrive
really works. In the real world, inputs from the dynamic stability control (DSC)
systemeach wheels rotational speed, steering angle, the vehicles
yaw and acceleration rates, and whether the brake light switch is activatedare
fed into an electronic controller. If slip is detected, an electric servo motor
exerts pressure on the multi-plate clutch inside the transfer case to transfer
torque to the front wheels. This unit, claims BMW, not only acts more quickly
and positively than a viscous-clutch, but makes it possible to use the unit
in more situations because the clutch pack can be fully open, fully engaged,
or at any level in-between.
Under normal driving conditions, the driving torque split is 40% front/60%
rear. With full traction at each axle, the maximum torque each can achieve is
50%, though this can shift within 100 milliseconds to 100% at one axle if its
opposite is on an extremely slippery surface, like glare ice. The xDrive system
is calibrated to quell understeer or oversteer as well by sending torque to
the rear or front wheels, respectively; its application greatly reduces the
intervention of the stability control system, which applies individual wheel
brakes and reduces engine torque to keep the vehicle headed in the intended
direction. (The X3s DSC system also has an added function designed to
keep an errant trailer in line.) Compared to the all-wheel-drive system found
on BMWs 3 Series, xDrive is nearly transparent.
Size Matters
Though its apparent when the X3 and X5 are parked together that each appeals
to a different customer (the X3 buyer is younger in spirit, if not years), a
quick comparison of dimensions tells an interesting story:
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X3 3.0i |
X5 3.0i |
Wheelbase (in.)
Length (in.)
Width (in.)
Height (in.)
Curb weight (lb.)
Interior volume (ft.3)
Cargo volume (ft.3)
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110.1
179.7
73.0
66.0
4,023
96.1
71.0
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111.0
183.7
73.7
67.5
4,652
97.6
69.0
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In many ways, these vehicles are nearly interchangeable, though the X5 feels
and looks considerably larger, and offers a V8 engine option. Base prices for
the X3 line start with the $30,995 X3 2.5i and jump to the X3 3.0i at $36,995.
However, a fully loaded version of the top model will set you back an eye watering
$49,520. BMW expects most heavily optioned models to cost about $42,000.
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| Though posed like a lion, and surprisingly capable for a crossover vehicle, most X3s wont see dirt unless their owners make a wrong turn. Thankfully, on-road performance is superb.
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An inline six in either 2.5-liter, or 3.0-liter displacement power the X3 (3.0-liter shown). Putting out 184 hp (2.5) or 225 hp (3.0), the engines are powerful enough, but challenged by the X3s 4,000 curb weight.
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Under the Skin
Buyers have a choice of 24-valve, aluminum inline six cylinder engines, both
based on BMWs M54 architecture and sporting variable intake and exhaust
valve timing and a duel-resonance intake. The 2.5-liter puts out 184 hp @ 6,000
rpm and 175 lb-ft of torque @ 3,500 rpm, while the 3.0-liter produces 225 hp
@ 5,900 rpm and 214 lb-ft of torque @ 3,500 rpm. Both are mated to a standard
six-speed ZF Type H-6 manual, or optional five-speed Steptronic automatic transmission.
Just dont expect to win any drag races with the 2.5 engine. Its
pulling around 4,001 lb., and the automatic-equipped version takes a leisurely
9.3 seconds to go from 0-60 mph.
The front suspension is a new version of the double-pivot strut layout found
on the X5, and 5- and 7 Series sedans, with aluminum forward lower links to
reduce unsprung weight. In the back sits a multi-link design similar to that
found on the 3 Series, suitably reinforced and with aluminum upper transverse
links. To strengthen the areas where the subframes attach, BMW engineers added
a large thrust plate in front (it also serves as a skid plate), and dual diagonal
braces in the rear.
Engine-speed variable-assist power rack and pinion steering is standard, with
vehicle-speed variable-assist available as an option. The brakes are 12.8-in.
discs in front, 12.6-in. in the rear, and tire sizes range from 235/55R-17 to
the Sport Packages 235/50R-18s. The X3 3.0i has an additional option that
fits V-rated 235/50R-18s up front and 255/45R-18s in the rear, and deletes the
speed limiter, which allows the manual-equipped version to reach a top speed
of 139 mph.