I'm no moral philosopher but my view on this dilemma is that the moral position is to be a considerate citizen - some people can keep all laws but still be a pain to their neighbours in society while others can break the law and yet still not cause ripples of annoyance. I rather like the idea that "Rules are made for the guidance of wise men and the strict observance of fools."In principle, then, the only reason to keep to the law is that you might get caught? It's funny for codgers my age because we were taught that there was some sort of moral duty involved as well.
In this context I guess that means worrying more about not causing other road-users a problem than the exact wattage of the motor or top speed.