So, general rule of thumb: If you are forced to start off a story with an intro that goes something like "ANOTHER story about ______" probably should write about something that more people can learn about. But, for the general public, the story of quattro is not common knowledge, which is justification enough for me to continue typing. And for the community that is bored of hearing the story of the rally car, I will let you know in advance that this article is about the evolution of the drivetrain.
Right, anyways, quattro. Quattro has historical significance. Okay, that was quite a bit of an understatement. It was more than significant, it was truly revolutionary. For those that do not know, the AWD system known as quattro, designated with a lowercase q, differentiating between the original Audi Quattro, the rally car that started it all, is the first and possibly the most prestigious full-time AWD system ever manufactured on a large scale. Still leading today in modern AWD technological developments, quattro is advanced. Newer models that feature the latest quattro system included in generation VI.
If you are interested in the story I mentioned briefly in the introduction, basically all you need to know is that Audi entered a rally championship in the 80s and they defeated the best team by bending the rules slightly and using an AWD car developed from military vehicles off-road systems, after testing showed that the car handled loose surfaces and corners much better.
1) Quattro I (1981-1987)
Used in the Audi turbo coupe, the first generation of quattro made its debut in the rally car. Its production debut in the Audi 4000 in North America, later the Volkswagen Quantum (Passat B1) in the US dubbed as "Syncro" which would later evolve into 4motion. It featured an open center differential, manually lockable in the center console, an open rear differential also manually lockable, but a open front differential that featured no lock. When all three are unlocked (aka one of the wheels loses traction) the car will resist movement. If the center is unlocked and the rear is locked, then the car will not move if one of each front and rear wheel loses contact. Vice versa, the car will not move if both front or both rear lose contact. If both center and rear lock, then the car will not move if all but one front wheel loses contact, in extreme cases.
2) Quattro II (1988-1997)
This featured a Torsen 50/50 center differential, and the same rear and front differentials. The technology principle remained the same, but the new center differential allows up to 75% torque transfer to either axle, improving performance. Last seen on the 1997 C4 Audi S6.
3) Quattro III (1988-1994)
This was featured exclusively on the Audi V8, the predecessor of the Audi A8. The system, that featured different configuration for manual and automatics, only activated if all but one front wheel lost contact. This generation was engineered exclusively for this vehicle, marketed as a specialized system. Including also a center planetary differential, which was new, pushing the Torsen differential to the rear.
4) Quattro IV (1995-2005)
Considered the true chronological successor to the second quattro, this generation was first seen in the infamous Audi RS4 Avant, it featured the first electronic detection system in the rear differential, that automatically sensed when you lost traction and adjusted accordingly by applying one brake to the spinning wheel. It used the same 50/50 Torsen center differential for AWD models.
5) Quattro V (2005-2010)
Major changes applied this year, a 40/60 center differential, and electronically controlled front and rear differentials. We also saw Audi's Vectoring quattro system, used in its high performance models. This ingenious technology used torque vectoring to allocate torque across the rear axle. This means that there is a system of gears and clutches that creates a shift in the differential, allowing even more distribution of torque across each wheel on each axle. This system was actually manufactured by a third party, Magna Powertrain. We saw this on the Audi S4 B8 (2008).
6) Quattro VI (2010-present)
Audi's latest quattro system was first seen on the 2010 Audi RS5. This features Audi's "Crown differential", replacing the outdated Torsen center differential. This new differential can send up to 85% or power to the rear and 75% to the front. This greater range of versatility improved functionality at higher speeds, increasing safety ratings in almost all conditions. This is now seen in the A6, A7, and A8. This generation can also be seen coupled with Audi's new 4-wheel steering system, capable of turning rear wheels up to 5 degrees.