"Unfortunately the faster you get, the more energy it takes to maintain constant acceleration."
I'm not sure what you mean by this. You could also say "the slower you get, the more energy it takes to maintain constant acceleration". Constant means ongoing, so as long as it is constant, you are going to have to expend more energy.
Unless you mean that somehow, you could determine your absolute speed by how much you accelerate for a given expenditure of energy, but wouldn't that violate relativity?
I'm not sure what you mean by this. You could also say "the slower you get, the more energy it takes to maintain constant acceleration". Constant means ongoing, so as long as it is constant, you are going to have to expend more energy.
Unless you mean that somehow, you could determine your absolute speed by how much you accelerate for a given expenditure of energy, but wouldn't that violate relativity?