GET OUT THERE.
At BMW we believe that powering all four wheels makes driving safer and more engaging, an approach we started in 1985 with the BMW 325i 'Allrad'. Over time we've developed new technology to make our all-wheel drive system react faster, more intelligently and with greater precision.
The intelligent all-wheel drive system, called BMW xDrive, offers a new dimension to driving enjoyment, and makes your journey safer when confronted by adverse conditions such as a rain-soaked motorway or snow. It's available across a range of BMW models - from the BMW 1 Series Sports Hatch through to the luxury of the new BMW 7 Series - and as well as providing peace of mind, it also lets you enjoy the power of your BMW on every bend.
All-wheel drive brings greater safety and peace of mind, as well as a more responsive drive to every journey. By variably powering all of the wheels depending on their grip, slippery roads become less treacherous and more of the power of the engine can be enjoyed as the car exits bends. We call this xDrive and it's been around for longer than you might imagine.
Where it all began.
In 1985 Mikhail Gorbachev came to power, Boris Becker won Wimbledon for the first time, and BMW introduced the BMW 325i 'Allrad', our first four-wheel drive model. Its full-time four-wheel drive system - sometimes called an all-wheel drive system - split the drive power in a ratio of 37% to 63% between the front and rear wheels. And when one set of wheels slipped but the other gripped, visco locks provided an almost rigid connection between the front and rear wheels in order to improve traction and stability.
Throughout the 1990s we refined the technology, replacing visco locks with electronically controlled clutches for a faster, more efficient response. The result is that today's BMW xDrive system is one of the most sophisticated and intelligent all-wheel drive systems around, being able to vary the power between the front and rear axles by as much as is needed, up to 100% to either axle. This gives excellent traction on slippery surfaces, from damp roads through to snow and ice. To explore the engineering behind BMW's xDrive, visit the Technology page, or jump straight to the models with xDrive.
TECHNOLOGY TO DRIVE.
The idea is simple, the technology advanced.
BMW's xDrive system powers all the wheels in a 40:60 split between front and rear to give better grip, which in turn improves handling and cornering. It's a simple idea, but to get the best from it power needs to be able to vary between front and back axles, and between the left and right sides of the car.
An electronically controlled gearbox and multi-plate clutch system allows BMW xDrive models to vary the power between the front and back axles. If wheel slip is detected, xDrive reacts in a tenth of a second to redistribute power to the axle with the most grip.
Dynamic Stability Control.
What happens though when powered wheels start to spin? BMW models with xDrive have a range of technologies, such as ABS and Dynamic Stability Control (DSC) that detect and limit wheel slip. Dynamic Stability Control detects a spinning wheel and applies the car's brakes to limit spin.
The system also activates if it detects understeer or oversteer, i.e. if the car is not going where the driver is steering, allowing the driver to regain control of the car, often without even being aware that the system has kicked in. It's important to note that DSC doesn't give better cornering, but instead is a safety mechanism, helping the driver regain control in tricky situations.
Dynamic Performance Control.
In addition, some BMW xDrive models are fitted with Dynamic Performance Control. This works in combination with DSC, but rather than braking the spinning wheel it uses a series of electronically controlled clutch plates to speed up the slower moving wheel. This is known as torque vectoring and gives smoother turns; for example on a bend more power is given to the outer wheel, because that wheel will have a grip advantage. Or if understeer is detected, more power will be directed to the inner wheel, so that traction with the road is regained.
Different driving requirements get a combination of power sources; for example, short distance city driving can be completed purely electrically, while longer journeys or any speed above 78mph (where permitted) rely on the petrol engine. At lower speeds where a burst of acceleration is required, the electric motor will kick in to support the petrol engine.