Thursday, December 18, 2008

Do You Need All-Wheel-Drive?

Many folks, especially those considering Subaru or Audi cars, ask whether or not they should get an All-Wheel Drive (AWD) vehicle. Really, that depends on what you need to do with your car. If you call me and I find out you live in Vail, CO, it's a no-brainer that AWD will really be useful for you. Calling from Modesto? Well, it gets a little more complicated.

What is AWD? On a really basic level, it is the same thing as four-wheel drive (4WD), which many trucks have. All four wheels are powered by the engine and help move the vehicle. This means that you have twice as much contact surface with the ground, and if it's slippery, then you have a much better grip on the road. If you only had one-wheel drive, and that wheel got stuck or was slipping, then you'd be pretty well stuck. With AWD or 4WD and modern tires, it's pretty unlikely that all 4 wheels will get stuck, and so the other powered wheels can help you get loose and back on the road.

So what is the difference between AWD and 4WD then? That's sort of complicated. Let's just say there are a few main differences (of course there are exceptions too):

1. AWD is usually full-time, or always on. You can't turn it off. 4WD is usually part-time, and you have to stop and engage it.
2. AWD is usually found only on cars or SUVs that are built from modified cars. 4WD is usually for serious offroad trucks.
3. AWD, during normal driving, usually splits the driving power between both axles (20%-80% or 30%-70% are common). 4WD during normal driving is usually just powering the rear wheels.
4. AWD can sense if you are slipping a wheel and put more power back there on the other wheel, the one with grip. With 4WD, you have to manually turn on the 4WD.

What does that mean, really? It means that AWD gives you excellent road grip at all times, especially when you hit some slick pavement that you weren't expecting to. So AWD is a pretty amazing option for places where the roads can get slick.

Are there disadvantages? Yes, AWD adds weight and cost to a car. This means the fuel economy suffers. Also, AWD cars tend to wear out their tires much faster than normal cars. And if you live in L.A., it's not doing you much good because it's always sunny!

Of course, some folks in L.A. go skiing, and some folks in Vail don't drive when it snows. So this is not necessarily as simple a proposition as it looks.

Have a question about whether an AWD car is for you? I'd be happy to help you out, just drop me a line for a free consultation.

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