Dear Tom and Ray:
I'm writing to you from hot and sunny Phoenix. My wife and I currently own a 2004 Subaru Forester. We bought an all-wheel-drive vehicle because we hope to be living someplace where it snows within the next few years. We love the car, but the gas mileage isn't spectacular because of the AWD. However, the owner's manual talks about a way to make the car work in front-wheel drive only: by inserting a spare fuse into the fuse box when you need to drive on a spare tire, so that the AWD system doesn't get ruined. Our question: If we put in this extra fuse to deactivate the AWD and therefore get better gas mileage, are we running the risk of damaging the AWD system over time? -- David
TOM: Well, having lived in the great frozen North for all of our miserable lives so far, we can't imagine why you'd want to move to where it snows. Unless you make your living selling Bronko Nagurski Long Underwear.
RAY: You've actually identified a problem that many people aren't aware of, David: All-wheel-drive vehicles are more expensive to own.
TOM: When you have all-wheel drive, you add an additional set of drive-train components. Those components add weight to the car, which decreases your mileage. They also can add to your repair costs, because there are more things to break.
RAY: So if you live in, say, Florida, Arizona or Southern California, you do your commuting on paved roads and you don't work for Mutual of Omaha's Wild Kingdom, you probably want to skip the all-wheel drive and save yourself some money.
TOM: A lot of people figure, "Well, it can't hurt. And maybe I'll be in a situation where it will be useful sometime." But they don't realize they're paying for that all-wheel drive every day in lower mileage.
RAY: Now, as you've discovered, David, Subaru does provide a way to deactivate the rear drive shaft. But unfortunately, it really won't help your mileage. Even though you can disconnect the rear drive-train components from the transmission, those parts are still turning (it's just that the rear wheels are pushing them, rather than vice versa). AND you're still carrying all of those parts around with you. So you still have the weight AND some of the friction of the AWD system, even when it's disconnected.
TOM: So I'm afraid you're out of luck, David. What CAN you do? Make sure your tires are properly inflated, be sure your engine is tuned and running well, and take that 1,000-pound snowmobile out of the back of the car until you actually make your move North.