I response to what BillT posted about the temperature of the fuel. I just read an article debunking this myth as inaccurate. Their premise was that the tanks are stored underground and just about anywhere on old Tera Fir-ma, the temperature of the earth below 50" of depth is a constant temperature and will have little effect on fuel being more dense at lower morning temperatures.
In other words, as Gasman has stated, it ain't going to give you more gas in your tank.
Most of the fuel myths you hear are bogus. I'm no expert, just someone who pumped gas in another life. Stations have two grades of fuel in tanks, lo-test and hi-test and any octane delivered in between is a percentage mix of those two grades.
We can't buy anything that doesn't contain at least 10% ethanol here. I've never concerned myself with it. If I had a high end restored muscle car I'd worry. For my daily transport, I don't really care where I buy gas. It's like a proctological exam these days anyway.
Hold your breath, it'll be over soon enough...the exam I mean! Gas prices have only begun to go up my friends.
http://finance.yahoo.com/family-home/article/112266/gas-savings-tips-that-don%27t-actually-work?mod=series-e-article