I use the Flying J and Sam's club.
- The Sam's is close to my house and averages about 10-15 cents cheaper per gallon than the other gas stations in the area. About $6-$9 dollars off an average RV fillup.
-Flying J is about 4 cents off per gallon. Flying J is usually a few cents cheaper than neighboring stations but the discount is about $4 off the average tank.
-I don't have a PenFed card but that would be about $10 off a fill up.
I just realized I have put way too much thought into this and must have too much time on my hands.