You are assuming that the same rules that apply on your car apply to the Universe as a whole.
That is not necessarilly true.
For example there was a period of the Universe's history called the "inflationary" perios where it expanded many times faster than the speed of light.
The speed of light is a maximum for objects in our Universe, it says nothing about the universe itself.
Don't confuse Dark Matter with Dark Energy.
Dark matter is matter that we know exists from gravitational behaviour of things like Galaxies. We just can't see it and don't know what it is. There are a few good candidates but we don't know which it is.
Dark Energy is much more puzzeling it refers to the Energy that is causing this accelerated expansion, or the physics behind it.
The first is likely to represent some changes to the physics we know, the second may well be some significantly new science. Perhaps a fith fundamental force or a major modification to the law of Gravity at large distances or a better understanding of "vacuum pressure" something like that.