I don't jump in often but have some experience with the older Audi/Bimmer.

My son totaled the '94 CS100 Quatro last February. The car never leaked and required only routine maintenance. It was in prime condition with 115K on it, snow tires, etc. It had the SRS warning light going on. I jumped it out. When he totaled the car, both air bags deployed as they should and saved the two front seat passengers from injury.

I would have to add that the AWD system on the Audi's was very progressive in that time frame. My sister is still running her '93 CS80 without issues.

BMW AWD systems are based on the Audi system from what I understand. With any AWD, you are going to pay more for parts and work and need more frequent interventions, IMHO. So unless you see routine snow/ice, they are not cost effective.

My '95 530i with 4 snows does great and doesn't seem to be as needy as the AWD versions of any make..........

You spends your moneys and takes your chances......