According to the fuel-savings app GasBuddy, Monday is actually the best day to save money on gas, and it’s particularly beneficial to hit the station in the mornings, since prices could start rising by the afternoon.
Fridays are the worst day to fill up your tank, likely because stations are trying to get a few more bucks from people looking to fill up before a weekend getaway. The app notes that those who normally fill up on Fridays can save between 20 and 30 bucks a year by switching to Mondays.
The best and worst days can depend on where you live though, with Saturday being the worst day in 16 states, and Sunday being the worst in 12