Elf Sternberg

Oh! And important note: I routinely buy gas on Tuesday night. It's the night after the lowest-demand day of the week, and the day prices are lowered if they're lowered at all. Prices go up more or less instantaneously, but usually don't drop until the following Monday night/Tuesday morning.

At least, that's what Real Simple magazine claims. I'd do more research, but I've been topping off that way and it seems to be doing no harm.