Lectric, I have an EX Sedan, is yours a 2 or 4 door? My grill block is just pipe insulation jammed into upper grill areas on my car, you'd barely notice it if you weren't looking. And take your tires up to 38-40psi, adjust how you drive and you'll save 10-15% right now. How much can you mess with your car? I'm not going whole hog with mine cause there's a 40% chance I'll sell it in a year or 2. I do love my Civic though, it's the best compromise of size, safety, performance, reliability, and styling of any car out there. For $9,000 used 2 years ago, it's been great. I was driving a Sierra 1500 Pick up before, and the fuel savings alone over the truck has saved me at least $6,500 in the 55,000 miles I've put on the Honda.
Major side note, I just changed my cabin air filters. You really want to check these particularly in Florida, I think it will really boost your AC performance if they're dirty and clogged. Here's a link to a U-Tube video that was a "Shoot, is that all there is to it" moment for me. NAPA had them on sale for $16.50 2 days ago.