the 4 motion is very good...in a passat. in say an r32? not so much as it is a front drive car first...rear is kicked in when needed(haldex)

As I mentioned earlier, "quattro" and "4-Motion" are marketing names. Audi does not use it's own system in all of its cars and the same could be said of VW, at least in the past. No matter which system is used, they still call it by their brand name.

The reason for this is that they share platforms. The Golf, TT and A3 shared the Golf platform, thus they used the VW AWD system. The old Passat was based on the Audi A4, so it used the Audi system. I don't know about the current Passat, as it is all new and may use the VW Haldex clutch-based AWD.

Getting back to the two main types of all wheel drive, you have the full time systems based upon a mechanical differential in the middle of the car and the part time systems, that use a clutch to divert power to the other end. There are some bastard arrangements that use a clutch to deliver power to both ends all the time but I don't really like these. The notion of partially engaging a clutch all of the time doesn't appeal to me.

Randy,

I like Audi's quattro system and don't like VW's Haldex-based systems. Drive one of each and see what you think.

JR

i have, the original quattro (i had an 83) and the LONGITUDINAL quattro/4 motion cars are the same...that is the BETTER setup
the transverse stuff(a4/a5 chassis (aka r32/tt) the haldex. There are different controllers available to alter this system (blue one) to be more like the original quattro setup

Most manufacturers awd setups are not truw awd, they are front wheel drive untill they need rear help. Subie makes an excellent awd setup, the longitudinal quattro(4motion) are excellent setups

Toauregs have another variant and they are VERY good
watch the video.

I've seen good things posted on sites re the Honda "Super Handling All-Wheel Drive" (SH-AWD). It features what Acura chief engineer Shiyouji Tokushima calls "Direct Yaw Control," also known as Torque Vectoring.

anybody know about the AWD system on the BMW xi (2001 - ??) and ix station wagons?

They had visco center differential in older cars and open differentials between wheels.