With AWD, in addition to the drive axles in the front, you have a driveshaft coming from the trans in the front of the car, going to a differential/transfer case, with 2 drive axles in the back, so down the road, you have to worry about a rear transfer case/differential maintenance, axle shafts/cv joints/etc, more weight for all of this means less gas mileage, slightly slower acceleration, and more costs down the road when the stuff breaks in 10 years. My personal opinion on how it detracts: tire wear will be all over the place, and almost impossible to try and keep up with making sure all 4 tires are rotated properly all the time to keep the same tread depth. Plus, if you are going around a corner, and let's say you lose control and the back end swings out, with awd, the rear wheels being driven will only cause further back end swing than fwd. Now supposedly the computer can sense which wheel of the 4 is slipping and applies power to the wheel with less slip. I don't see any advantage to awd, unless you live in a hilly area in the north half of the u.s. and the roads become snow covered more than several times a winter. Keep in mind, when trying to slow down, all wheel drive does nothing for you, you rely only on your brakes, so the only thing awd is for is acceleration on slippery surfaces so your tires dont spin. But think about it, with front wheel drive, if your tires spin, you do NOT lose control, because front tires spinning do not cause a rear end to slide sideways.... rear tires losing traction cause a rear end to slide sideways, so I want nothing to do with applying any power to rear wheels at any time. There is no noticeable noise difference inside the cabin, that I can tell between fwd and awd.
