I have an '04 A8 and started having problems after we had a few days of below zero temperature in the Midwest. The car is parked inside the garage and never encountered any problems starting the car but in less than a minute the engine would just die with no warning light indicators. It would start easily within seconds only to die again within 1 minute.
Tried putting HEET. Have a full tank of gas. Battery is fully charged. Current temperatures in Indiana have been in the 20's and sunny.
Would appreciate any advice.

 

Fuel doesn't freeze until you reach -97*F, so i really doubt thats it.
You should have the dealer diagnose it.

 

Thank you.
It is in the dealership and I will relay their findings.