A few years ago I had a car that anytime the temperature dropped below freezing at all it wouldn't start. The problem was a little different because the starter wouldn't turn over in my case, but the reason was that there was a little bit of water where it wasn't supposed to be and when it froze it was freezing the starter in place.
If you guys have a little bit of water on one of your electrical connections somewhere, the expansion when it freezes may be enough to break the circuit.
With the problem only occurring right around the freezing point I would say that there is a pretty good chance water is involved somehow.
I was always taught that when diagnosing a car, start with the cheapest solutions first and see if they work. Maybe try putting a few bottles of heat in the gas tank, drive the car for a bit, and see if the problem is fixed. If it's not then you're only out like $5.
Last edited by AlaskaBMW; 02-09-2012 at 06:51 AM.