"All Wheel" versus "Four Wheel" drive.

Dear Car Talk

Dear Car Talk | Dec 01, 1991

Dear Tom and Ray:

My driveway is quite steep, and I have an old, beat-up four wheel drive truck that I use to get in and out of it in the winter when there's snow or ice on the ground. I also have a sedan that I use at all other times. My truck is falling apart and my car is six years old, so I'm comtemplating the purchase of a four wheel drive vehicle to replace both of them. I've noticed that there are vans and cars on the market that advertise "all wheel drive" as opposed to "four wheel drive." In questioning the salesmen about the difference, I get a lot of confusing answers and quite a few shrugs. Will an "all wheel drive" get me up and down my driveway in a winter storm, and what is the difference?

RAY: Ahh, the "salesman's shrug." That's a close cousin to the "mechanic's shrug." I guess the guys in the service bays have been teaching it to their white-belted, plaid-trousered, showroom colleagues.

TOM: Well, here it is in a nutshell, George. A "four wheel drive" is a two wheel drive vehicle that can be switched to four wheel drive by moving a lever or pushing a button (or in some old heaps, getting out, locking the front hubs, and running around the vehicle counterclockwise three times). Your old truck is four wheel drive. It's two wheel drive until you move the shifter from "2WD" to "4WD." Then the engine's power is delivered evenly to all four wheels.

RAY: "All wheel drive" usually means that power is delivered to all four wheels all of the time. It's sometimes called "full time four wheel drive" too

TOM: In "all wheel drive" vehicles, the distribution of power can change. Take the All Wheel Drive Dodge Caravan . The Caravan's front wheels get 90% of the power under normal conditions. But if the front wheels start to slip, up to half of the power is automatically re-routed to the rear wheels to get you out of the slippery situation.

RAY: So the answer to your question is yes, an all wheel drive vehicle should be able to get you up and down your driveway in the winter. Aside from the Caravan, Audi has always made wonderful all wheel drive cars, and Subaru has been making both four wheel drive and all wheel drive cars for many years.

TOM: Or, if you're worried about getting through really deep snow, you might want to consider some?thing with more ground clearance, like the four wheel drive Ford Explorer. Even though it's technically a truck, it's the most car-like vehicle in that class. But unless there's a lot of dog sled traffic where you live, an "all wheel drive" sedan ought to suit your needs just fine. Good luck, George.

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