[brucepick]

Don't blame it all on the water. Blame a lot of it on your increased need/want for electricity and a/c for defrost.

This past summer I did an alternator delete with two substantial deep cycle batteries to provide for all the electrical, and also an ac compressor belt delete (after the compressor seized up).

Now I don't get nearly as much of an mpg hit in rain as I used to. Yes I run down the batteries faster running headlights and fan and wipers, but fuel economy doesn't drop as badly as it used to. All that electricity and of course the a/c for defrost used to run off the engine. No more!

Having done those deletes, I can say from experience that a lot of the mpg hit due to rain is from the accessories we want to run in the rain.