Ok, I have a question, which may have been answered somewhere, sometime, already, so bear with me.
In driving down the freeway, with a vacume gauge, it is clear that the highway's are not really flat, in most cases and that their are constant very minor slopes which an average driver never even notices. In driving with a light foot, it seems to me that it should be much more fuel effective, to keep the throttle at a lean setting, which on a slight slope will cause the car to slow, imperceptibly. However, when you get to the down side of the slope, the slight change, allows the vehicle to pick back up a little bit of speed.
The consequence is that if you can handle driving +5 to -5, it seems to me like you should be able to do better on mileage.
Taking this notion one step further, it seems to me like on longer up's or down's, if it is necessary to change the throttle position, it would be better to accelerate down the grade and just maintain, or slightly loose speed on the up grade.
Has anyone done any testing on this sort of circumstance's, or drawn any general conclusion's which might be insightful?