No start after freezing temperatures

My 1992 BMW 325i has developed reliability problems in well below freezing conditions after two previous winters with no problems.
One month ago temperatures got below -20c and the car engine would turn over just fine but no ignition.

Today even with some gas-line antifreeze in the tank I experienced another no start at -15c and after trying each day, as temperatures gradually increased, still no start at -4c. I don't no why it shouldn't start at just -4c!

When the engine turns over there is just a hint of the engine firing up. I have to think it is related to no fuel getting to the engine, but why is it so suscpetable to freezing. I don't know if it really matters but I have been using gas with 10% ethanol content.