The Fed Govt clearly has the right and the duty to regulate interstate commerce as Leah noted. It's one of the key duties of the Legislative Branch. Any company ( vehicle maker ) that want's to do business on an interstate basis has to accept this oversight.

Congress also has to the right to pass laws presented to it by the Executive Branch to protect national security and to foster the well being of we the citizens. If this means mandating less use of oil or increased use of nuclear or decreased emissions then those are questions of a vote amongst themselves based on our input to them. The citizens of MI, OH, IN might not be infavor of some initiatives that negatively affect them but benefit the rest of the States. Here the majority voices its opinion.

Lifetime fuel usage: 2.1 GPC ( 1.99 recent )