Normal bad driving conditions are heavy rain, snow, and ice, commonly found on the roads during periods of bad weather. Not offroading, climbing rocks, etc.
What exactly makes AWD/4WD that much better than FWD/RWD?
Why is 4WD better than AWD? Don’t you have to “turn it on” and if so, isn’t that worse if you hit a patch of ice/standing water/whatever, than AWD?
I vaguely understand that all axles vs only the front/rear axles are engaged, but I don’t understand the difference between AWD and 4WD, and not really why some roads are “chains required unless AWD/4WD” – is it that much safer that you wouldn’t need chains on the tires?
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All wheel drive cars typically have a series of differentials, one to split front/back, and another to split left/right on both ends. This allows for a variable amount of power to reach each wheel, and each wheel can rotate somewhat independently of the others.
A 4wd car uses a transfer case to evenly divide the power between the two sets of wheels. This ultimately means that with a 4wd car, you always get the same number of tire rotations on all the wheels over the same time. While this sounds right, if you’re cornering, your inside wheels need to spin less. A 4wd car will experience slippage and loss of traction since they will have wheels that rotate the same amount but try and cover different distances.
This is why AWD can be always-on, but 4wd is usually a selectable mode — it has a specific use case, and it can make things worse outside of that use case.
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