Perhaps a totally nutty idea, but I thought I would mention it... Part of my job is new ideas and once in a while I hit on something that works out. Just have to keep trying. I am told Ted Turner has a 90% failure rate.... I recently saw a story on solar cookers on the TV and was wondering if something like that could be adapted to keep the engine warm. The premise is to take a hood, cut openings into it, inset clear plastic into the cutouts, then color the top of the insulator black (or replace it?) to see if it would keep the engine compartment warmer than say a painted black hood. The hood on a Prius appears to have an air space of about 1.5 inches or so. If it would work, all sorts of interesting custom designs could be used. If anyone thinks it is feasible, let me know I can can work on a prototype. We have a fiberglass division in our company and they have built carbon fiber hoods before. I do a fair amount of designing for laser burnounts and I could come up with something for a metal version.