As I stated in another thread, there have been multiple warnings about not getting your money's worth at the pump if you fill up in the afternoon. In the afternoon, the pumps don't compensate for the warmer temperature, and you are actually not getting as much gas, but paying the same amount. Gas expands the warmer it gets. If you bought gas in the hot afternoon, by the next morning you will have less in the tank. Depending on how hot the afternoon is versus the morning temperature, and how much gas was purchased, you could be looking at more than a couple gallons difference.