Having had 10 BMW's with xDrive ... following 2 Audi's with quattro ... 3 Jeep Grand Cherokees with different versions of Jeep's multiple awd / 4 wd options ... and two XC 90's ... I can say with some confidence that there are only two things wrong with xDrive:
- Knuckleheads who drink the marketing Kool Aid think xDrive / quattro controls winter traction. It does not. As others have correctly noted, your tires are the only part of the vehicle which contact the road. And so-called "All-Season" tires are by definition compromises. They excel at nothing, and suck at pretty much everthing. Fact: Any of my 4 prior RWD BMW's would outperform your xDrive, (or your neighbor's quattro), because they were always mounted with dedicated winter tires. The exact thing is true regardless of whether we're discussion xDrive, quattro, or Volvo's lousy awd system.
- No one reads the owner's manual. And folks who don't read the ower's manual don't realize there is a setting you can select in your xDrive vehicle which will significantly improve traction in snow. And no, I won't tell you what it is. You should RTFM yourself, as you may find some other goodies in there.