>I also live in soggy Seattle and drive a '74. My heating system is in pretty 
>good shape and once the engine gets good and warm, it will defrost if I'm 
>cruising. But not during city driving or sitting in a traffic jam. So, I 
>usually carry a towel or two.

Get a plastic soap dish, like you take camping and put in a sponge that fits
decently.  Keep the sponge wet with windshield washer fluid, the low temp
stuff. Any sign of fogging and a wipe will clear it off and keep it away.
This works in winter to clear frost off the inside too.  Sometimes a bit
wavy to look through, might have been something I ate though.  tim, learing
at you.