I noticed that your car has a carb rather than fuel injection. Many carbs richen the mixture significantly when manifold vacuum goes way down. I noticed this when I hooked my digital voltmeter into my oxygen sensor circuit and watched the values change at different throttle positions. At about 3/4 throttle- the voltage started jumping up (this means unburned fuel).
This richening effect by your carb might cancel out any gains from opening the throttle and reducing pumping losses.
To me, it seems to blow those arguments against DOD (cylinder deactivation) out of the window, that say that because you need more throttle angle to maintain speed on less cylinders, you'll barely use any less gas.
I remember The RoadWarrior..To understand who he was, you have to go back to another time..the world was powered by the black fuel & the desert sprouted great cities..Gone now, swept away..two mighty warrior tribes went to war & touched off a blaze which engulfed them all. Without fuel, they were nothing..thundering machines sputtered & stopped..Only those mobile enough to scavenge, brutal enough to pillage would survive. The gangs took over the highways, ready to wage war for a tank of juice