Originally Posted by JohnVidale
The xDrive is 235 lbs heavier - but a load of people in my family weighs a lot more that that, I would account for 75% of it. More relevant is that the xDrive is FASTER, not slower - 5.7s to 60, rather than 5.8s to 60. Maybe you have the power robbery backwards?
1 - 0-60 times are very subjective. It's much easier to launch an AWD car, but case in point Car and Driver got 4.7 seconds out of a 335i.
2 - AWD draws more drivetrain loss than RWD, this isn't novel to BMW or any other car manufacturer. The same engine is in both cars, the AWD drivetrain needs to turn more gears, more shafts, which result in more parasitic loss due to physics, which means less power to the road. You may be able to get a better jump off the line with AWD, but over a distance the RWD car is faster, and the power delivery is apparent if you actually drive them back to back.
At the end of the day you're probably getting around 10% less power out of the X-drive, so by the time you've left first gear and the car has hooked up traction, the car is slower.
The next response I'm sure is going to be "I never drive my car fast so I don't care" which is fine - but trying to make the point that AWD is faster and cheaper is silly. The only justification you need is "I drive a lot in the deep snow and want this for my own piece of mind"