Yellow battery indicator light came on while driving car in 35 degree weather after a week of sitting in garage (holidays). I pulled over, read the manual and it said this could cause battery light to illuminate. I called the dealership service to ask them, they said possible reason. I decided to drive across city to dealership, 25 minutes away. On HOV lane, red warning lights flashing to pull over then 5 seconds later everything went black. No electrical, no engine, car died. VERY DANGEROUS!! Read later that this has been happening on Audi A6 (& other models) for 2+ years. Towed to dealership and they have had 1.5 weeks and still not fixed.