Obama to allow states to set own emissions standards?

President Obama today signed a presidential memorandum ordering the EPA to reevaluate a request from California to be granted a waiver from the Clean Air Act; which would allow California to set her own standards for car emissions beyond that dictated by the federal government. If such waiver were granted, the remaining 49 states would be able to follow suite. Therefore, the possibility of 50 individual state emissions standards and 1 directed by the Clean Air Act would exist. How could anyone expect the car industry, let alone the EPA, to keep up with the enforcement of such standards?

I am all for setting strict efficient emissions standards but I feel it should be done on a federal level. The present status quo of law directs that in the end, the federal government supersedes the state. Why not come up with a realistic number for emissions that would be enforceable?! The current course of action by our new president seems to be more trouble than it is worth.