Hello. Regarding the AWD system on theTaurus, I have been very pleased with it. I have a 2011 SHO that I purchased with 57,000 on it. I have put 90,000 more on it and it has given me no issues. Running good all season tires on it, I have had absolutely no issues with it here in West Michigan. The car is very sure footed in all 4 season and inspires confidence even in the worst of weather.
Acording to the owner's manual it is a full time system. I have never noticed any wheel slip or a transfer of power from front to rear or vice versa. The car is always, solid, dependable and sure footed.
I have heard the Fusion's AWD system is different but I do not know for sure, I have not researched it myself.
For an all wheel drive car, it I were not driving this Taurus, I would be driving an AWD Lincoln, Ford or a Subaru. My wife is on her fourth Subaru. I won't go back to a 2WD or FWD again.