BMW’s expanding X model range has been an outstanding success story since the original X5 was launched in 1998, with the mid-range X3 alone having sold 1.5 million copies across two generations since its 2003 debut.
In styling terms BMW’s X cars have been on a clear convergent path of late. Where the original X3 looked distinctively different from big brother X5, and the smaller X1 also arrived with a clear and unique identity, the second generation X3 took on the persona of a shrunken X5, with the current X1 looking like a smaller version of that.
The clever part of the third generation X3’s styling has been dropping the side glass line down under the front door mirrors so that the car now presents a lighter, airier appearance both inside and out. So while the new model maintains a close family look, the more prominent ‘Hofmeister’ kink on its D-pillar gives it a unique styling feature that echoes the first generation X3.
In line with the current BMW styling mantra, the kidney grille is now larger and more prominent, and sees the first use of the recently introduced 3D grille on an X model. The front lights, now subtly chiselled at either end, turn the corners in a way that gives the front a softer more rounded look. Standing out in stark relief, particularly on a dark coloured car, these light clusters appear to float in space on either side of the grille and above the compound curves of the one-piece front bumper moulding.
The current BMW styling ethos draws a taut, muscular look to the areas above the big wheel arches, and this is visually reinforced when the optional larger and wider 20-inch wheels and tyres are fitted. These are standard on the X3 M40i, with even larger 21-inch wheels a factory option.
The new X3 (Internal code G01) is based on the 3-Series platform, and even the front and rear axles are basically the same. But as a 4x4 requires significantly greater ground clearance of 204mm, with a fording depth of 500mm for off-road driving, engineering changes have been made to increase the ride height and reset the geometry accordingly.
Big wheels were part of the recipe that gave the sporting models in particular, of the outgoing X3/X4 (F25) range a rock hard ride on anything less than billiard table smooth tarmac. “We put a lot of work into redefining the relationship between the body and unsprung masses, and ended up with completely different spring and damper rates, as well as elastokinematics,” explained Alexander Meske, head of integrated application of chassis dynamics. “The valving system of the variable dampers has a lot less friction now, aimed at improving ride comfort without detriment to the handling.”
“The tyres are new as well, their construction also aimed at improving ride and handling,” he continued. “We have 18-inch wheels on the base X3 models, with 19, 20 and 21-inch options. As the sporty model, the M40i comes with 20-inch cast alloys as standard.”
“We did consider air suspension in the beginning, but the cost and extra 50-70 kg such a system would add made this untenable,” recalls Arno Keller, the X3 project chief. “In the end we managed to reach our objectives of better ride and handling with conventional steel springs and active dampers.”
Being tall vehicles, off-roaders have significant frontal area, and the X3 is no exception. Even so, thanks to the greater incline of its front windscreen and significant wind tunnel work, it is able to claim a leg up over direct rivals with a class leading 0.29 Cd. This figure is for the base X3 with its skinnier 18-inch footwear, and the M40i with its big 20-inch wheels and other sporting addenda degrades that to a still decent 0.33. Slipping through the air more efficiently also helps to reduce wind noise to the benefit of cabin refinement.
A constant conundrum for engineers designing a sporting SUV (Sports Utility Vehicle), or SAV (Sports Activity Vehicle) as BMW likes to call their X cars, is the conflicting demands of tarmac handling, which requires relatively modest roll angles, and off-road ability, which requires good axle articulation and traction.
From an on and off-road traction point of view, the new X3’s rear axle electronic locking differential is a boon as its operation, both on and off-road is precisely calibrated with the appropriate software. Standard on the M40i and optional on other X3 models, this allows the xDrive system to send from 0-100% of the engine power to either axle to optimise available traction.
On a flat, dry surface and on a constant light throttle the system as installed on a normal X3 runs in rear-wheel-drive only since disengaging the front drive saves fuel. Add some throttle or begin to corner and about ten percent of the power is sent to the front axle to stabilise the car.
Naturally the more driver oriented M40i model, the first ever M Performance X3 variant, has a greater rear power bias in the bends, the system adopting a 40/60 percent power split in just five milliseconds. The computing power required for the mass of data is governed by a FlexRay system that operates alongside the normal CAN-BUS.
“In Adaptive mode, the system will automatically default to Sport mode when you begin turning into a bend,” says Alexander. “In this mode we can ‘pre-condition’ the chassis in this way to optimise ride and handling for occupants without the driver having to constantly fiddle with the mode selector.”
Despite being larger than before the new X3 weighs around 55 kg less. In typical BMW form weight distribution is fairly even so around 900kg rests on each axle. The weight saving largely comes from greater use of aluminium for panels such as the doors and rear hatch, while lightweight, high strength steels are used in critical areas like the roof panel to increase stiffness while reducing weight.
The ultra-high strength steel roof panel removes weight from the highest point of the car, helping to lower its overall centre of gravity, while further weight saving comes from the use of hollow anti-roll bars, and cast alloy components such as the suspension turret tops. The front and rear sub-frames remain steel.
On the subject of materials, the new X3’s environmental sustainability credentials see around 50% of the alloy engine and chassis parts made from recycled aluminium, while 10% of the thermoplastics are also created from recycled material. The home for all these new components is a steel monocoque whose greater torsional stiffness is a good starting point for the improved suspension.
As before, the front suspension is by McPherson struts, with a five-link rear axle, and this has been refined geometrically in the search for improved ride comfort and handling. There was not much wrong with the handling before, but the ride quality left a lot to be desired, with the sporting version being really edgy on bumpy roads.