I too contemplate things when I drive only I concentrate on Philosophy and sociology. I suppose since I can't understand people's motivations I try to come up with reasons for things, but enough of that.
I have always thought Dark matter is a bit suss. Physicists were studying space and couldn't come up with a reason for what appeared to be, and this might be extremely exagerated, 95% of the universe's weight. It just seems to me to be cheap that they then explain
"oh well the thing is there is this thing called Dark matter that makes up all the extra weight, only we can't detect it or see it. It makes our sums add up though if we assume it exists"
Pity I wasn't taught such a thing in college.
"oh well on the face of it my math doesn't add up but you see there is an unseen variable that if included results in 1+1=3"
All I know of Gravity is that it is the weakest of the 4 forces. After all the entire gravity of Earth acts on us yet we can easily lift things, dependent on weight, and lift our own mass.