Alot of truck drivers on here.
Here our speed limit is 70, trucks 60, we drive 65 in the the Rover, 70 in the Volvo. I agree that driving to slow is just as dangerous driving to fast.
We used to make a 272 mile round trip to my in-laws on a regular basis and it took 1/2 tank of gas at an average speed of 58mph.
100 miles expressway and 36 miles of state and county roads.
The type of tires you have make a huge difference too.