An empty tank is an empty tank and obviously requires you attention today, BUT if you have the option to fill up when you want, then all across the country, there is a best and worst day to do it, if you want less hassle and more savings

 USA Today says generally speaking, fill up on Monday morning on your way to work.

In a recent study, GasBuddy assessed 150,000 gas stations to determine the best and worst days of the week to fill up in all 50 states.

Early in the week and early in the morning show the lowest prices and least amount of traffic.  USA Today says, "On Fridays, especially around 5 pm, traffic is at its worst and prices often spike in part because some stations are seeking to make more money ahead of weekend trips."

You won't get rich taking this advice but every little bit helps, right?  If you switch from Friday fill ups to Monday mornings you could save $20 to $30 more year.

There are some states that buck the trends but Washington falls in line with Mondays being best and Fridays being the worst.