My first BMW was an '88 535i with limited slip differential. When I put 4 Nokian Hakkapillitta 2's on, there was no stopping that car from moving through any snow or slippery condition! And I long lost count of how many "all wheel drive" vehicles I went around, all stuck trying to go up the steep hill near my home. Even my '04 Pontiac GTO (also rear wheel drive with LSD) was great even though I'd bought the BMW as a winter beater to keep the GTO parked.
All wheel drive comes in different forms, and the most common ones are no better than front wheel drive. Especially true when no one bothers to switch to true snow tires on all 4 corners.
OK there is miss understanding of four wheel drive and and all wheel drive.
Four wheel drive has been around since just prior to WWII. The Willys Jeep like my 71 year old CJ 2A shown below was the first US vehicle to have it.
This basically set the design for four wheel drive. There is a gear box and then a transfer case, with drive shafts going to front and rear. There is a differential for the front wheels and one for the rears. But, and this is the important point: - THERE IS NO DIFFERENTIAL BETWEEN THE FRONT AND REAR WHEELS. This means that four wheel drive should only be employed on a surface like mud or snow where there can be slip of the wheels. Otherwise stress build up in the drive. My neighbor was unaware of this and was using his ATV routinely in four wheel drive, and recently came over to me to say he started backing up his hill and there was a crack and his ATV would not move. I went over and looked underneath and the rear diff was split wide open with the cogs, bearings and oil on the pavement. Re education commenced.
Now a four wheel vehicle is actually more dangerous on ice when four wheel is engaged. They should never be driven above 40 mph in four wheel drive under any circumstances. This applies to all trucks and large SUVS like Suburbans.
In 1967 a small UK sports car company Jensen invented a transfer box with a a differential between the front and rear drive shafts. This was the Jensen Interceptor.
1967 Jensen Interceptor
This was licensed to Land Rover and in 1970 the world's first SUV with All wheel drive appeared.
The 1970 Range Rover. My father bought one right away.
The development of the all wheel dive differential system was a game changer. This allowed the vehicles to drive on all four wheels simultaneously without problems. It greatly enhances road handling and safety on ice and wet roads. Up in the North country I can certainly attest to that.
Now the Range Rover had a lock that could be engaged to lock all four wheels in heavy snow or deep mud.
These days the transmission computer instantly spots a spinning wheel and stops it. I'm totally amazed at what a steep icy hill my Equinox can climb without difficulty.
Actually it is more effective than the standard four wheel drive on my old Suburban.
All Subarus use this system. It is used on all SUVs now, or at least is an option, SUVs like the Honda CRV, Chevy Equinox, Chevy Traverse, Ford Escape and many, many others.
For gas conservation newer models have a switch that puts them in standard front wheel drive when travelling on dry roads, as a gas saving measure. So you engage all wheel drive on wet, icy and snow covered roads.
Lastly a word about snow tires. Again this is not understood. Snow tires do increase traction in snow significantly. Unfortunately they reduce traction on ice and compacted snow which actually makes them more dangerous than a good all weather radial tire designed for the North Land.
When I arrived in Manitoba and in my early years in ND, I used studded snow tires in the winter. As tire technology improved I switched to using high quality all weather radials. In this part of the world tire selection is vital. American made tires are generally best up here and European tires tend to be a disaster. But I don't stint on tires. Having a good relationship with an experienced local tire dealer is I find very important. In the winter here tires are not created equal by a long shot.