The fact that you took my 100mph at 1100rpm literally
OK, I'll remember to ignore anything you post in the future that closely resembles facts, numbers, statements, opinions, etc because it might be in jest.
Unless there are constant elevation changes, with your foot you can just keep it at the same spot and the car speed up/slow down normally while using the same amount of fuel, CC will open up throttle on uphill sections to keep same speed.
The CC will open throttle uphill and close throttle downhill, resulting in constant speeds. Your constant foot would slow down uphill and speed up downhill, resulting in varying speeds.
Varying speeds mean you spend more time at slower speeds and less time at faster speeds, hence your average speed drops compared to a constant speed.
Varying speeds mean you are either too slow uphill or in risk of speeding tickets downhill.
Varying speeds mean you get excess punishment from aerodynamic drag during the downhill sections without being compensated on the uphill sections.
Here's an example: If you constantly go 100km/h you will do 100km in one hour. If your speed varies, let's say you switch between 90 and 110, you will have to do 45km at 90km/h and 55km at 110km/h to get 100km done in one hour.
The penalty for going 10km/h faster is greater than the reward for going 10km/h slower, and you do more distance at the higher speed. As a result your consumption will go up.
Additionally, if there is a speed limit equal to or slightly lower than the average speed you run the risk of tickets at the higher speed.
[narf mode]actually constant fuel flow = lowest consumption.
If you let the fuel flow constantly while going downhill at or near terminal velocity you are doing nothing to speed up, that fuel is entirely wasted.
constant acceleration = fastest arrival, as you did not mention road conditions and the need to actually stop at your destination or the fact that car is limited in its top speed
[/narf mode]
You people have speed limits to worry about, good luck with your constant acceleration.