Well, of course you were using your God-given free will. But it's not relevant to the discussion with the officer, who is concerned strictly with administering the consequences of your free-will choice.
I'm not sure what you mean by "if there wasn't a speed limit..." If the law doesn't permit him to take action with respect to your speed, then it doesn't. But when I was growing up in Montana, there wasn't a NUMERICAL limit--just the requirement that speeds be "reasonable and safe." And officers could certainly ticket drivers for unsafe speeds, and did. (80 mph on a two-lane highway with hills and curves was usually good for a ticket.)
Moving on to the parallels, or lack of them, to the Garden of Eden story, we ought to recognize that the prohibition of fruit is in fact meant to represent something else: the acquisition of knowledge of a limited type, which is proverbially dangerous. The consequences are not analogous to being ticketed for speeding; they're more analogous to getting injured or killed in an accident caused by driving unsafely.
God's prohibition, in the story, is not an arbitrary restriction but a warning of the consequences, just as the old Montana speed law was a very clear statement that driving unsafely was wrong precisely because it was unsafe.

