It used to be that you could tell what category a vehicle belonged in just by looking at it. A truck was a truck. A sport/utility was a sport/utility. There was no such thing as a crossover, so anything that didn't fall into those first two categories was a car. Along those same lines, when looking at four- versus all-wheel drive, it used to be easy: One was serious, and the other was a gimmick. All that has changed. Today, categories have become so fractured that there are vehicles that could be referred to as a car, a 4x4, or a crossover--depending on whom you ask. The weird part is that each answer could be right.

The manufacturers themselves aren't helping matters much when their respective marketing departments are more concerned about what sounds good, rather than what's accurate. And what role does the Society of Automotive Engineers, supposedly the premier authority on all things automotive, have to play in this confused world of vehicle traction systems and the name game? It used to be simple -- if you owned a pickup truck with big lever shifter on the floor and had to get out of the truck to turn the front hubs from "open" to "lock," then you had a four-wheel drive.

Then along came the SUVs in the 1980s and 1990s, with electronic in-cab four-wheel-drive controls and shift-on-the-fly capability. With the touch of a button from the comfort of your heated driver's seat you could switch from two-wheel drive into either an all-wheel-drive mode (with a center viscous clutch) or a mechanical locking four-wheel-high-lock mode, giving both front and rear driveshafts equal amounts of engine torque. And your front hubs engaged automatically. Some OEs went so far as to offer limited-slip or locking differentials in both front and rear axles to give their vehicles true four-wheel drive, meaning all four wheels could deliver traction at the same time no matter what the surface.

Tremendous advancements in traction control technologies were also being made. The same computer software that controlled the fast-improving anti-lock-braking systems could also control both slow and higher-speed tire acceleration response. These systems used super-smart sensors to monitor and control wheel speed during stops and starts, whether in low-range, high-range, or in standard rear drive.