Congrats on the improvements!
Keep an eye on the coolant temp if you completely block the grilles. (I wouldn't recommend covering it all, actually.)
And thanks for reminding me about the door handle idea. It's only going to make a tiny improvement - probably not detectable at the gas pump - but every little bit helps. One idea might be to simply make a "form" that smooths over the handle and sticks magnetically to the side of the car.
As for the solar idea, it could certainly work, but it would be really pricey. See this thread for ideas/opinions:
http://ecomodder.com/forum/showthrea...roof-4097.html