I've never used any kind of de-fogging solution on the car windows so I don't know what would help once everything was fogged up. The secret for me has always been setting up the heater to prevent it in the first place. It's a lot easier to prevent than it is to control once it gets really foggy.
Usually, in my experience, if the heater is set right, a small car like the Civic (or any car for that matter) should be able to be de-fogged pretty quickly, but from what you say, it's fogging up almost right away when you get in the car and then is hard or impossible to control. I wonder if the fresh/recirc door in your heater is stuck in the "recirculate" position.
Does your A/C work okay? Did it blow lots of cold air back in the summer? Just you and your mom in the car shouldn't be causing an uncontrollable problem if everything's working and set right.
Here are conditions which should give max defog if the heater-A/C is working correctly: A/C compressor turned on with blower set to full speed, set to Defrost, fresh air, temp set to warmest setting.
If it's *VERY* humid outside, sometimes once the car's warmed up and the heater can perform at it's max, the A/C can then be set to Recirculate as long as everything else is still set at the max settings, but don't leave it set that way if you turn the A/C down or off.
Assuming setting the A/C and heater correctly, I'd guess either the A/C needs a charge or the heater doors aren't moving into the correct positions. Also could be a blower problem or blocked vent. Are the side defroster vents open and pointed at the windows?
With lot of movement of the driest, warmest air available, there shouldn't be a problem.
One other thing that may be contributing to the problem could be whatever the windows have been cleaned with. It may be forming a base for the moisture, preventing it from being able to dry fast enough.
I've stopped using window cleaners on any windows, car or house. I just use two microfiber towels - one damp and one dry to wash and polish the glass and the windows are much easier to clean and re-clean. They also stay clean much longer.
Last night, my back window fogged a little bit and I switched the rear heater to high for a minute to move the air back there and it cleared off right away, so maybe switching or eliminating window cleaning chemicals is another solution to the problem.
Good luck and let us know what happens.
Happy Holidays!
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Chuck
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[This message has been edited by ckonarske (edited 12-15-2001).]