All-wheel drive used to be a specialized attribute for a select group of vehicles that would see some of the worst conditions possible for four wheels. Now, however, it seems like one of the most crucial features for most consumer models. And that’s a good thing. More grip invariably leads to safer roads, and with demand for this technology increasing, it seems to be getting better and better.
Audi is often credited with creating one of the first high-volume production AWD systems when it launched the Quattro, a vehicle that first saw success in the harsh conditions of rally racing. Nowadays, one of Audi’s main rivals, BMW, has it’s own technology to boast about, called xDrive.
This video explains how “Dynamic Stability Control Sensors” are able to detect which wheels are losing grip, and respond by diverting torque through a multi-disc clutch to the appropriate axle for maximum traction. Nearly 100 percent of available power can be sent to either axle in this fashion.
BMW likes to think xDrive is the most technically advanced AWD system out there. But is it better than something like Audi’s quattro system?
The truth is, it depends. Instead of electronically actuated clutches like with xDrive, quattro is based on a torque-sensing (Torsen) center differential, which uses physical differences in frictional resistance to vary torque between the axles. It’s far less complicated, but every bit as effective, which is why it’s a system that’s still in use today.
Click past the jump to read about BMW’s AWD-equipped vehicles.
Typically, cars churned out by BMW’s M Division are high-powered,RWD petrol burners with gobs of performance. The M550 xDrive has only one of these traits, but thankfully, it’s that most important one.
Under the hood, you’ll find a turbocharged six-cylinder diesel engine tuned to deliver 381 horsepower and 546 pound-feet of torque. That’s good enough for a 0-to-60 sprint under five seconds, with exact figures of 4.9 seconds for the wagon and 4.7 seconds for the sedan. Top speed is electronically limited to 155 mph. Incredibly, these numbers are accompanied by a fuel economy rating of 44 mpg, partially enabled by an auto engine start-stop function. Putting the power to all four wheels is an eight-speed Sports automatic transmission.
The exterior is tweaked with the addition of an M performance body kit, with a new design for the front and rear to help smooth air flow. Two xenon headlights flank the mandatory BMW kidney grille. Lightweight 20-inch wheels fill the fender wells. Inside, there’s copious M badging, plus a leather-wrapped steering wheel with a pair of paddle shifters. There is also the addition of Alcantara sports seats, four-zone climate control, a USB media interface, and a hands-free system.
So then, in summation – this car is fast, gets great fuel mileage, it looks good, it’s got AWD grip, and it has a nicely appointed interior. Sounds perfect, right? Well, there’s a reason: the car starts at around 80,800 euros, which equates to roughly $91,000 at current exchange rates (2/17/15). But if you live in the U.S., too bad, because this thing won’t make it stateside.