Saab 1994 900 (New Generation) cold weather driving

When the temperature goes below 50 degrees it does not like to start. I have replaced the battery and had the electrical systems checked for a drain.



I would like some ideas on what to check next. The car has been looked at by 2 different reputable garages who have not seen anything obvious





Does the engine not crank over at all, or does it crank very slowly, or does it crank at the normal rate, but never actually catches and fires up?

BC.

If I only had a brain. This car is not used for days at a time. When the temperature is above 50, it does not fail to start. As soon as the temperature drops below 50, the battery seems to drain. I can jump it and drive for 5 minutes, shut it down for and hour and it will start. If I leave it for a day, I have to jump it again.