We are very familiar with vehicles that have traction on all tires, lets agree that its 4 wheels. Most folks want traction on 4 wheels in our climatic conditions.
Ever wonder how it came about?
The classic vehicle with traction on all the wheels was usually a pick up, or a Suburban, or the early versions of what we know today as SUV's. In most instances the vehicle had a 4 speed truck type manual transmission with first being the creeper gear, a 2 speed "lockable" transfer case that could accomodate a PTO (power take off), ideally a positraction in the rear, free wheeling hubs for the front wheels, and for extreme applications a positraction units would be installed in the front differential.
The rule of thumb was narrow, tall tires to have ground clearance (do you remember 7.50x16 truck tires), accompanied by skid plates, especially for the gas tank (s) and the areas with the least ground clearance.
If you are concluding that these vehicles were horrific on the highway you would be correct! If you concluded that they would endure a good amount of off road abuse, with regular weekly maintenance to tighten most components that were rattled loose during the week...you would be correct again.
How did these vehicles evolve to what we understand today as an AWD vehicle?
 The 4 speed manual with the creeper gear began evolving towards a 3 speed automatic, easier to off road with an automatic, less tiring to plow snow. Imagine how fast this vehicle would accelerate with the transfer case in Low, the automatic shifts all its gears, put the transmission in Neutral, shift the transfer case to High, the transmission in D, keep on going.
 Free wheeling hubs (disconnect the front wheels its was literally a 2 wheel drive vehicle) were next to go, totally unpleasant to forget engaging the front wheels and having to deal with snow, mud, rocks, one wheel refusing to engage.
 The driver at the time had an innate understanding of the various sounds a 4x4 would make in its off road progress, and usually if it started "shuddering" in its forward progression especially in snow...backing out was a wise decision.
 For years it was body on frame, solid axles, transfer case configuration, although the leasure vehicles were more luxurious, and 4 wheel traction and a higher stance was a major priority compared to off road capabilities.
 Yes...the classic 4x4 still exists mostly in pick ups.
 Manufacturers have converted the "street 4x4" to an AWD configuration responding to the need for luxury, traction on all the wheels, excellent highway behavior, independent suspension front and rear, and technology hading the task of distributing power to the wheels with traction.
 The transfer case...still need "something" to compensate for the differing speeds of the front and rear wheels, took a while for the transfer case on street version to evolve from 2 speed to single speed, and then the transfer case becoming a "clutch pack" to allow slippage and compensate for the speed difference.
 The street version is an AWD vehicle that delivers power to all 4 wheels, with computing power and AI controlling how the power is delivered to the individual wheels. In most instances its a unibody structure (no longer body on frame), with a FWD configuration (transverse mounted engine).
 The technology deployed to deal with the myriad of variables of a current AWD vehicle be it SUV, CUV, or car is truly impressive...from precisely controlling the torque going to each wheel, to balancing the torque from the rear to front several times a second to name a few.
Every self respecting gear head prides himself in the fact that he knows how to drive, understands a vehicle, is the consummate expert in shifting a transmission with a clutch pedal, will always hit the sweet spot of an apex every time...all the time.
There is an endearing sense of causality in mastering the control of a vehicle...or thinking that we have mastered the abilities of a vehicle. Folks actually pay to go play with a vehicle on ice and snow, to understand how a vehicle behaves in adverse conditions.
Must be the reason that genuine hard core gear heads have motorcycles, and derive an immense pleasure and satisfaction in riding a motorcycle...out in the wind, responsible for all their actions, keenly aware of their riding environment.
By now you know that The Colonel has been around for a little longer...lets turn it to him, and see what he understands about technology and vehicles.
Collapsing Steering Columns: If you are of an age that you remember bent steering wheels almost contacting the seat back, or head liner it was always a gory scene. A steering column that absorbed collision energy was a meanigful advance in safety.
Seat Belts: Remember the early lap belts which were considered of questionable benefit, since the upper body was not restrained. A pony car still being sold today, back in the day had metal side panels for the rear seat area (today immense plastic panels do the same thing) with the window cranks sticking out. You got it, rear passenger flew from one side to the other, the head lands on the metal, fortunately did not hit the crank.
Air Bags: First saw an air bag deployed in the mid 1970's when folks were refusing to wear seat belts, a demonstration up close of what happens when the vehicle stops abruptly (collision) and the passengers continue through the windshield or under the dash was very convincing. Fortunately it was all done with "crash test dummies". Back in the day, a deploying air bag was a violent incident...very violent.
ABS: First encounter with ABS was in the late 1970's as FMVSS 121 on HD trucks with air brakes, very cool at the time to see and hear it work, although is was not accepted on HD trucks. The first model year that certain cars had ABS brakes in Canada was 1985. A few years later had an opportunity to experience ABS under various conditions, yes ABS lets you steer out of trouble for one. In addition at highway speeds, is it just wet, is there ice, safe and simple with ABS to gently apply the brakes to see the outcome, could not do that with a vehicle without ABS. Agreed...some ABS systems were scary with the noise and pedal pulsation.
Brake Assist: A momentary distraction, the vehicle in front brakes a little harder that you expect, brake assist is very useful to avert an embarrassing situation.
Traction Control: The early days of traction control...very useful under slippery conditions, with patience and low speeds traction control is effective. Although human nature interprets traction control as an instant remedy to get out of situations. In many instances there is a disconnect between the right foot, and traction control. In addition to the disconnect between the vehicle with traction control, and the one with AWD.
Electronic Stability: How many manufacturers would put 20 inch wheels on SUV/CUV if the vehicles did not have ESP...think about it. Especially when the wheels are one size too big, and the tires two sizes too wide to achieve the "look". In snow trying to stop or steer this thing generates another look and activates enough computing power to fly a plane.
These are just a few...yes there's a lot more in a current vehicle...how often have the precedings saved you from an embarrassing situation?
If you are of a certain age that you remember the iconic Hemi 392, then you also remember Don Garlits, and the early Chrysler 300 letter cars. Needless to say that when you see the latest Challenger 392...for a multitude of reasons the car resonates.
Here is Jay Leno, and Ralph Giles having a bit of fun with a Challenger 392.