is it better to go with the flow on the hwy?

[Capcom]

Originally Posted by MetroMPG

my car's "sweet spot" for mpg vs speed is significantly less than 100 km/h. in fact i think it's closer to 70 km/h, though I haven't plotted it out yet. (it's on the list.)

In a modern fuel injected car, best mpg is at the lowest possible speed at the highest possible gear.

For a level road: My car has the best mpg between 50-60 km/h (31-37mph) at the highest gear. Between 50-60km/h speed if i am not not accelerating anymore my car's automatic transmission shifts to the highest gear and instant consumption reading from the trip computer is between 3-4 liters/100km
But of course when going uphill best mpg speed at the highest gear must be "increased" to 70-80 km/h (43-50mph) or even more due to the angle of the incline. If not: car stalls and downshifts to the 3rd gear resulting more fuel consumption.

By the way i guess air flow generated by the traffic helps mpg but of course we shouldn't get too close behind other vehicles for safety issues.