The color that gets the "best" mpg is the one driven by the "best" driver. Of course that color choice is obvious. However, since we're at the end of the model year you may have to compromise on the color or package. The bottom line is that every Prius is beautiful.
Get whatever color you want, but be sure to coat it with Zaino! I put the Clear Sealer on after washing Rudy, and I can barely touch the car without sliding right off it!! The wind just slips over him like melted Earth Balance (brand spread)... Oh, and RainX on the windshield.... That helps, too.
White or silver would be most fuel efficient if the rear panels were painted mat black so it warms the air behind the car causing it to expand pushing the car forward.
I think that the Magnetic Gray would provide the most mpg as all the large SUVs and trucks would "pull" you along.
Eric, I hope you snarfed that up (as long as doing so wouldn't be financially irresponsible for you)! The best "offer" I got here (through the Costco auto program) was $23,500, and I thought I was getting a deal based on the stickers in the Southeastern region (yes, I know that has a lot to do with it.) I did consider buying one in the SF Bay Area where my parents live, but the shipping would have eaten up whatever I'd have saved. (Driving it back wasn't an option as I'd have had to register it in California and then re-register it in Florida when I got it back.) If you're a Costco member you might want to see what kind of deal they offer. The best part of that whole experience is that it's "no haggle" pricing with rules about mark-up and disclosure. Really the only things that they can hit you with are the "Little Room" extras (warranties, service plans, etc.)
For whatever reason, there currently seems to be plenty of Priuses in the SF Bay Area and we had no trouble getting quotes near $22K (pkg#2) from multiple dealerships. We just went to the one closest to us (SFToyota). We didn't consider Costco, but should have!!
Give this man a cigar for posting the correct answer. This is pretty much the same theory of operation as a Crookes radiometer - Wikipedia, the free encyclopedia.