There are many all-wheel drive (AWD) systems in service. These include Audi’s Quattro, Mercedes-Benz’s 4MATIC, Acura’s Super Handling, and Subaru’s Symmetric AWD. BMW has its own AWD system called xDrive. The German car manufacturer claims xDrive takes all-wheel-drive drivetrain technology to the next level. But what sets xDrive apart from its competitors? What does xDrive mean on a BMW vehicle?
xDrive is BMW’s proprietary all-wheel drive system. It’s used in numerous BMW models, from the 2 Series to the X7, and even comes as a standard feature for some models.
An AWD system transmits power to all the wheels. Designed for use on roads, it can handle slippery conditions like rain and snow. Furthermore, it assists sports cars and other performance vehicles when they go from zero to 60 or make high-speed turns.
Like other AWD systems, xDrive uses a clutch-pack differential to adjust the torque between the axles. But while other systems rely on hydraulic pumps and motors to distribute torque as required, the BMW system uses electronic actuators with superior precision and better responsiveness.
Later versions of xDrive have a torque vectoring system called Dynamic Performance Control (DPC). DPC uses a planetary gearset to overdrive any axle or rear wheel that needs extra torque. Overdriving is a process where the wheels attached to an axle spin faster while the ones on the opposite axle rotate at a reduced rate.
The BMW xDrive system performs two jobs. First, it enhances the vehicle’s handling and stability, which becomes very handy when driving around corners in a hurry. Secondly, xDrive ensures the tires and wheels get the best traction possible, which improves control and handling.
Let’s take a closer look at how BMW xDrive works:
xDrive monitors how fast each wheel is spinning at all times. When the BMW all-wheel drive system detects the need to counter slippage, it will deliver torque to the axle or wheel with the highest traction.
The xDrive system can transmit as much as 100 percent of the torque produced by the engine to one axle, rapidly increasing traction for the vehicle. It can even concentrate all torque into the one wheel with the most traction.
When it isn’t redirecting torque to only one axle or wheel, xDrive splits torque between the two axles. Usually, the front axle gets 45%, while the rear axle gets 55%. The front-to-rear ratio shifts as xDrive adjusts the torque distribution in response to road conditions.
At the core of the xDrive system is a clutch-pack differential that sits between the driveshaft and the gearbox. Made up of multiple friction plates and controlled electronically, the clutch splits engine torque between the axles and wheels. It is geared toward people who live in colder climates and has traction issues on the road from the cold.
Compared to the center differential used by most AWD systems, the clutch-type diff enables xDrive to distribute power between the axles and wheels in any combination.
Of course, this capability will go to waste if xDrive cannot accurately gauge the wheels’ traction. That’s why the BMW-designed AWD system leverages a sensor network that looks at various factors, such as the steering wheel’s angle, the brake force, and how hard you’re pressing the gas pedal. Based on the sensor readings, xDrive distributes the correct amount of torque to the axle or wheel that needs it.
Aside from maximizing traction, xDrive makes high-speed turning easier and safer. Cornering causes a drop in traction, especially at higher speeds and on slippery roads.
When an xDrive-equipped BMW goes around a corner, the AWD system decreases the power supplied to the wheels on the inner curve. Not only does this help the vehicle move sideways, but it also gets the BMW out of the curve as fast as possible.
The xDrive system also prevents understeering and oversteering. When you corner, you might accidentally apply excessive power to the drive wheels. If that happens, xDrive compensates by shifting power to the opposite axle, thus correcting the steering issue.
If xDrive detects understeering, it sends less drive power to the front axle. On the other hand, if it detects oversteering, it sends more power to the front axle. Whatever happens, the xDrive system responds dynamically, adjusting the drive power supply to stabilize the vehicle.
xDrive also cooperates with other automotive systems like Dynamic Stability Control (DSC). A BMW-proprietary suspension control system, DSC measures the wheel speed and other factors through various sensors.
Readings collected by DSC’s wheel speed sensors go to xDrive, which uses the data to determine the state of the road. If it detects a difference in the traction between the vehicle’s sides, it will apply brake force to prevent potential wheel spin.
The xDrive system is a boon if you live in a state with lots of precipitation. Be it rain, snow, or ice, precipitation makes for slippery roads. Thankfully, xDrive can prevent the wheels from slipping and skidding across treacherous surfaces, keeping you safe when you drive while it’s raining or snowing.
xDrive also works well away from roads as it does on roadways. All-wheel drive has reached the point where it can compare favorably with 4-wheel drive when it comes to off-road driving. And xDrive can correct traction loss caused by loose soil and mud.
Furthermore, xDrive makes you more confident while cornering at high speeds and driving on low-traction road surfaces. That shot in the arm isn’t quantifiable, but you’ll definitely feel it.
In summary, xDrive brings a load of benefits that will vastly improve your driving experience and road safety. Its advantages greatly outweigh its drawbacks, which chiefly involve increased fuel consumption because of a 4WD’s heavier weight and higher power requirement. Even then, xDrive reduces its impact on fuel costs through weight savings and increased efficiency, making it well worth the minimal additional expense.
However, the complexity of the xDrive system requires that everything works properly. If even one part stops operating properly or becomes uncalibrated, the system might develop issues. Usually, the dash will display warning messages when xDrive stops working properly. Bring your vehicle to a trustworthy shop for repair.
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.