What's the difference between AWD and 4WD? I was handed the keys to the brand new BMW M5, which can actually switch between 4WD and 2WD! Nothing all that impressive for any truck drivers out there, ...

Which is it: four-wheel drive or all-wheel drive? The answer is more complicated than you might expect. Is the system part-time, full-time, or on-demand? Reactive or predictive? Does it use a ...