In my
first post to this forum, I postulated that in the absence of aerodynamic drag, climbing a hill as fast as possible is most efficient.
The reasoning goes like this:
It takes energy just to maintain a stationary position on a hill (when the brakes aren't applied).
The longer a vehicle is stationary on a hill and expending energy to maintain position, the more fuel is consumed.
To make forward progress, an amount of energy greater than the amount required just to maintain position on the hill is needed.
If you are creeping along at a snails pace up a hill, the majority of the fuel consumption is being used just to maintain position on the hill, and a very small fraction of that is making forward progress.
The conclusion is that climbing the hill at ever greater speeds results in a larger portion of the fuel being consumed in forward progress when compared to maintaining position on the hill. Reaching the top quickly means less fuel being consumed to merely maintain position.
That said, aerodynamic drag does exist and is a significant factor considering it is an exponential function. Not only that, but engine operating efficiency must also be factored in.
The conclusion is that the most efficient speed to climb a hill is certainly faster than as slow as possible, and likely slower than as fast as possible. The practical way to find out is to perform a test just like wmjinman and JRMichler.