I think the proper equation would be d - 55 = 0, if d=55. In the equation you gave d=0, not 55. Then again it may just be a question of semantics that is not relavent to the issue. I think there may be no way to prove there is an absolute frame because of Galilean Invariance.
http://en.wikipedia.org/wiki/Galilean_invariance
All the laws of physics are the same when traveling at a constant velocity. So then any constant velocity could then become this zero. Even if there was an absolute frame, there would be no way to show that it is different from any other frame because the laws of physics would be the same, if you assumed it was one way or the other. So then it is just personal preference as to where you would set motion equal to zero. Theoretically, you could say that there is no rest and everything travels at 1mph, then the car travels at 56mph. It would only complicate things, because the only difference that we are conserned with is that the car is traveling 55mph faster than you are. There is no reason why a car should travel something other than 55 mph faster than you are because of how we percieve zero.
If there was, laws would have to change the further we came from this true zero, but there is no sign of that. Values have the same relation to each other no matter where you put your zero.