Firstly, you're talking about tachyons. They are hypothetical particles used in thought experiments, not observed scientific phenomena. If you truly believe there are 'instances where the speed of light are exceeded', please link me to some hard proof - a scientific journal would suffice. I can guarantee you won't find any.

Your proposal of dark matter and dark energy to violate the principle of special relativity is, in itself a contradiction. Now, I'm no cosmologist, but from what I've read they're linked more so to Einstein's general relativity. It should also be noted that little is known about dark energy/matter, so all we have to go on is proposed theories. Most cosmologists agree that dark energy is causing the accelerating rate of expansion of our universe, and as this rate continues to increase, some surrounding galaxy's radial velocity will exceed the speed of light; this is because of a bending in space-time, and thus does not violate special relativity.

If you mean other sources of fuel to reach the speed of light than let me clarify: to reach the speed of light you would need an infinitely large source of energy. Since our universe is finite, that is not possible. Too little is known about dark matter/energy for it to hold any real sway in this debate.