there is no hybrid only law. In fact most all states have equal access of the road laws.
It is one of the reasons the pregancy parking is unenforcable since it discriminates.
Some local municipalities have implemented them - don't know if they can enforce it. I don't have them where I live as far as city-owned parking goes. Some private parking lots have it here - I ignore them, as my engine is an air/gasoline "hybrid". It really is just a stupid "feel-good" thing.