2011 A8 4.2; Shortly after a spirited downshift to pass on the highway, my coolant level warning light appears. I pull over to find a nearly empty reservoir. Having owned a 2004 Phaeton (4.2), I remember reading horror stories of the coolant/oil cooler plastic $8 part that would leak coolant; however, after 3 stops over 60 miles and 2 gallons of coolant/water, I thought I was hearing a hissing sound behind or under the oil filter. Any ideas?

1) Did Audi get rid of that horrible plastic pipe to the oil cooler with the D4 models?
2) If I stock up on 15 gallons of distilled water, will I limp my way 300 miles back home?
3) Does anyone have experience with coolant leaks near the oil filter?